I like to say that the two biggest things you can do to improve your fuel economy are learn to drive and modify your aerodynamics. Drag reduction takes a back seat to driving techniques, but no one is saying you can’t do both! Hopefully this will serve as an overview of basic sources of drag and the modifications that people go through to try and cut their Coefficient of Drag to more fuel economy-friendly levels.

Before we get into the sources and solutions for drag, check out this equation that describes the makeup of aerodynamic drag in a passenger vehicle:

• V = wind velocity in tunnel
• S = frontal area of vehicle
• E = wheelbase
• Cx = coefficient of drag
• Cy = coefficient of drift
• Cz = coefficient of lift

Now that you’ve seen that, keep it in mind, and on to the good stuff:

General Shape -
The shape of the car is the most important thing to aerodynamics. While you can’t do much about your existing car, you can consider aerodynamics when purchasing your car. Most cars, such as the CRX, will have Coefficient of Drag (Cd) statistics readily available to help in your decision making process. Just so everyone knows, the second generation CRX Si and DX had a Cd of .30 and the HF came in at .29. The difference here is due to the HF’s lack of a rear wiper.

As I said, there’s not much you can do about general shape, but if you’re up for it, there is one thing. This modification is called a boattail. One of the main principles in aerodynamic body shape is that a smooth, long, tapered surface should be attempted in order to keep attached flow through the end of the car. But, at the end flow is generally cut off abruptly, which is where a boat tail, a short extension of then end of the car, adds a greater length over which flow may taper. Though this isn’t done much, some great motivation for attached flow can be taken from Phil Knox’s modified truck.

Mirrors –
Mirrors contribute a huge amount to the aerodynamic drag of a car, especially for how small they are. There are several solutions to this problem. One such solution is to install smaller mirrors that won’t create such a large amount of frontal area and turbulence, as seen here: Another solution is to install folding mirrors (if you don’t already have them) and fold the mirrors back when you reach highway speeds. Also, you could just eliminate the passenger mirror, or both, using head turns to check before making lanes changes and performing other maneuvers. Many Insight drivers have eliminated their mirrors and replaced them with cameras so that they could still get an optimal vantage point without turning their heads. One note of caution: If you’re considering removing or altering your mirrors do a test drive before making the change permanent; you don’t want to get in over your head safety-wise.

Underbody –
The underbody is another big source of drag on most vehicles. Most underbodies are designed without care for aerodynamics, which is good and bad. Bad because most of us are starting off with terrible underbodies, good because there is a great improvement in Cd to be had from a full undertray.
Some cars, such as the Acura NSX come with full undertrays, but for the rest of us, “The contribution can be up to 25% of the total drag. Careful design can achieve a change in Cd of -0.02 on serial production cars.” Check out this Chalmers report as the source and for more information on underbodies and drag.

Cooling –
Particularly because of the shape and design of the radiator it causes a large amount of aerodynamic drag. Radiators are designed for worse case scenarios, scenarios most of us are never likely to be in, which is why a grill/radiator block can easily and safely be installed on most cars. Check out this article detailing my grill block installation to get a few ideas on how to do this. If you’re considering modifying your car for improved aerodynamics and fuel economy, this is the first place for you to start!

Tires –
Surprising, tires cause a large amount of aerodynamic drag. This drag can be reduced by moving to a slimmer tire and reducing area in the wheel well where turbulent flow can exist. Check out this thread for a great DIY on installing some rear wheel skirts. While that probably should not be discussed here, one of the main issues with wheels is that they cause a huge amount of turbulence, and if you can block air from getting to them that turbulence will be greatly reduced.

Deserving of its own paragraph, wheel covers are a stylish and cool way to modify your tires for fuel economy. Lacking a picture of some mounted on a car at the moment, check out this set on the right to see what you’re getting yourself into: They do work and your brakes will still cool themselves properly, so don’t worry about safety with these things. Happy hubcapping!

Unfortunately, I forgot to mention wheel spoilers. These are relatively simple things, designed to gently divert air under the car from ramming directly into the tires. They will not do much in terms of drag reduction, but the benefit is there, so keep them in mind when building an undertray.

Wipers –
As I noted previously, the rear wiper on the CRX makes a .01 difference in Cd. Consider removing it and treating your rear window with a product such as Rain-X. However, as I mentioned earlier with the mirrors, go out for a rainy drive without using your rear wiper before you decide to eliminate it completely. Some eliminate one of both of their front wipers and rely on glass treatments, but this is not something I could do. I will, however, endorse the idea that you remove the blades and keep them in the trunk, so that if it does rain you can simply pull over and pop them back on!

Misc. -
The radio antenna rounds of the rest of the serious drag contributions. Check out my writeup here to check out my antenna removal.

Final Notes -
Aerodynamic modifications are the most important modifications you can make to your car. Take them seriously and you can have a good looking car with greatly improved fuel economy. Good luck and send me some pictures when you’re done!

Replacing the thermostat is one of the easiest, cheapest, and most imperceptible ways to increase fuel economy. Stock thermostats, which generally open at around 180 degrees, are a compromise between performance and fuel economy. If you’re treating your engine kindly you can get away with installing a 195 degree thermostat in order to push your fuel economy up ever so slightly. Since most radiator fans will not turn on until a 210+ degree condition is reached, you should be fine under normal conditions.

Take a look at this graph relating fuel trim to engine temperature in Hondas. This offers some theoretical evidence of the savings, though it is generally so small that testing would be nearly impossible:

Purpose: A hotter engine runs more efficiently. By increasing the coolant temperature a few degrees we can improve the efficiency of the engine very slightly.

Time: 30 minutes

Tools:
- Socket Wrench
- Basic Metric Socket Set
- Pliers

Supplies:
- 195 Degree Thermostat
- Thermostat Gasket
- Coolant to replace that which you spilled

1. Take a look at your damn engine compartment. Find the thermostat housing. It’s in the middle of this picture, with the big hose going to it:

2. Get your pliers on the big clamp, move it off, and take off the big hose going to the thermostat:

3. Take the one side of the housing off (two 10mm bolts) and expose the thermostat.

4. Yank the old thermostat out with some pliers. Now you realize where all the spilled coolant will come from!

5. Put the gasket or new gasket on the new thermostat.

6. Put the thermostat back in and replace the housing. Tighten it down not to much, but just enough. Torque specs help!:

7. Look at your completed work.

This article will be the first in an ongoing series examining fuel economy claims made on the internet and in advertising. I begin with this specific page because it’s suggestions are most damaging to the true hunt for improved fuel economy and because it carries more credibility as a “third party” source. While products will be analyzed in the future most people already carry some doubt of their advertised fuel economy claims, which means that consumers are less likely to be suckered into believing those claims. However, there are many people who present themselves as lifelong experts in the field of fuel economy. Why not believe them, with all their experience? What it comes down to is that the claims, and not the person should be analyzed. I make no claims to be a great thinker or industry insider, I am merely a student from Dartmouth College, 2010. Nevertheless, logic and critical thinking have led me to certain conclusions about many fuel economy enhancements, some of which I will share with you today.

The first source of such suspect claims will be “Tips for Economy (Methods for Great Mileage.)” This article outlines several tips that purportedly will double gas mileage in any vehicle. Feel free to read through the text on your own before reading this analysis. However, the text will be quoted in full on this page in order to be broken down and examined piece by piece. This examination will be done as completely within the scope of the text (and not referencing other pages on the site or other resources with similar claims) as possible. While outside sources will be used to contradict or confirm what is written within the SmartGas article, it will not be criticized because it shares opinions with other articles.

While reading this analysis there are a few things that should be kept in mind as they are important points and will often be referenced:

• use of inflammatory claims that have little to nothing to do with fuel economy;
• repeated blame of big business for tricking the people, yet support is still giving, very specifically, to certain devices, companies, and people;
• a complete lack of references supporting the written claims.

Conveniently, the article is a numbered list. The quote portions shall be indented (and rather obvious).

Significantly Improved Mileage:

1.  Big Oil and the  American Car Manufacturers and others do NOT want you to get good mileage. They will strongly object to the following extraordinary techniques. They have a huge vested interest in keeping mileage low in order to stay rich and get richer–at your expense. The following secrets are now yours. Conservation is the key to our Nation surviving the fuel shortages that are coming. Mileage = Conservation. Actually the shortages are already here. It is becoming common knowledge that state governments are hesitant to improve mileage because the less gasoline your car guzzles, the less tax money the government collects. That makes government part of the growing problem.

The troublesome thing about this statement is not it’s correctness or incorrectness; the troublesome thing is that this has nothing to do with fuel economy. However, this tirade is the first gas mileage tip offered in the article. The very first. And all it amounts to is this: “Dear Readers, you may want to improve your mileage, but the world is working against you.” It offers no advice.

However, it does do something. It excites the reader. This preface acts much like the image of body bags and black lungs do in anti-smoking ads. Once you shock your audience they are more welcome to your ideas. Because really, if you’re telling someone how to avoid black lungs, an actual black lung is a big motivator.

2. Two ounces of acetone per ten gallons of diesel fuel will greatly reduce soot and improve fuel mileage an average of 10-25 percent. Acetone is a very slow burning additive. Yet it improves MPG and power. You notice a gain in smoothness and performance. Acetone does help to make alcohol fuels more combustible by absorbing the water content that inevitably accompanies alcohol. In cold weather you may encounter wax or icy crystals of paraffin in your diesel fuel that can stop your engine. Acetone helps to keep the wax suspended in solution. See the graph on acetone use. Never use clear plastic bottles to hold gasoline or acetone. Those will melt. Use the plastic bottles from isopropyl alcohol to use as your acetone containers. But never use acetone that contains benzoate, an ester that inhibits vaporization and raises the flash point up to the point where the additive is ineffective. They often do that to acetone so the higher flash point resists good vaporization. Remember, bad mileage means they sell more fuel. It seems to be all about profits.

Acetone will be dealt with more completely after point number three, however, there are a few things specific to diesel that ought to be mentioned. As the article states, acetone does mix with water and ethanol (view source) so it can be said that it causes these ingredients to “fall out” of the gasoline. However, it does not absorb it and magically turn it into gasoline. It can, however, cause water to deposit in the tank or fuel pump, causing failure of the pump (view source).

It is also worth noting that at the end of this point the article states that some acetone has anti-vaporization additives that are meant to prevent people from getting good gas mileage. Evidently this article holds the position that acetone is manufactured primarily as a fuel additive and not as nail polish remover or paint stripper. But then again, it is logical that the “Big” nail polish remover executives would be profiting from low gas mileage.

3. Two or three ounces of acetone added into 10 gallons of gasoline will increase mileage about 25-percent or more. Your MPG will increase and performance too. You can expect a smoother running engine to last longer by obtaining better vaporization and mileage. Those little ounces reduce the amount of unburned fuel to near zero thereby saving rings and walls. When the exhaust valve opens, nearly all of your fuel should have burned already. Please use a small stainless measuring cup and long ATF funnel to protect your paint. We buy the Klean-Strip or Dupli-Color brands of acetone in paint stores or hardware stores such as Home Depot, Wal-Mart or K-mart. Not from drug stores. There are bad brands of acetone out there because it has been doped with impurities and lacks that strong acetone smell. My favorite place is Sally Beauty Supply for 100-percent pure acetone. Sally is worldwide. It comes in pint, quart and gallon cans, often on sale. The quart cans are easy to pour. Pour the acetone into bottles to keep in your trunk but only fill them outdoors. A technical grade of acetone is often best in my experience. We also get Klean-Strip cans of xylene to add to the acetone. We are now also using equal amounts of xylene per 10 gallons. If your acetone does not give good results, get the good stuff from Sally.

Before discussing the actual merit of acetone it is worth noting the brand bias shown in this section. Firstly, the author states that he buys a certain type of acetone. Secondly, he states that you should not buy acetone from drug stores. Finally, he states that if it’s not working you bought the wrong acetone and that you should get some from a drugstore named “Sally’s.” The part where this makes sense evades me, I am sorry to say.

Now, onto the discussion of acetone itself. The article claims that it can increase gas mileage upwards of 25% due to fuel injectors poor ability to vaporize gasoline. However, as discussed here and here the amount of unburnt fuel is as much as 1-2%, no more. The author states is “…that modern fuel injection systems already deliver this extremely fine fuel mist, thanks to years of intensive development. The average drop size from a typical modern injector is around 0.1 mm, almost invisibly small….” How could a 25% gain in gas mileage come from, at most, a 2% increase in fuel vaporization? It couldn’t.

This is also a fitting time to note that all testing is flawed, especially tank to tank road testing, which falls victim to an unbelievable about of environmental variables. I will discuss testing difficulties in another article later on, but for the moment this article does a magnificent job of summing up the issues with testing.

4. Only one unique oil in the world actually brings engine friction nearly to zero. That truly high performance oil comes from a small company in Santa Fe Springs, California called Torco International whose website is TorcoUSA.com. We recommend their MPZ oils and additives in all climates all year. We get it in 5-gallon pails. We use their racing and diesel oils in every kind of car and truck for better MPG. You can expect a 15 to 30-percent boost in mileage with all piston engines in cars,  trucks,  motorcycles, aircraft and heavy equipment. Plus a greatly improved life of the parts. NEVER use 5W-30 or 5W-20 oil because it is closer to a grinding compound than a lubricant. We always add Torco MPZ Magnetic Friction Reducer and a bottle of EAL Engine Assembly Lube every other oil change. Torco Oil is available at 562-906-2120 or 562-906-2130. Specifically, we use their petroleum base MPZ enhanced petroleum products. 15W-40 Super Diesel or 20W-50 TR-1 Torco MPZ racing oil for excellent mileage BUT only ONE bottle of 20W-50 synthetic. Just one quart of the synthetic per oil change. The rest is all Torco petroleum oil. Take your pick of these outstanding quality lubricants. We use a 12 oz. bottle of Torco EAL and a 12 oz. of Magnetic Friction Reducer for the greatest possible MPG in any vehicle. I add these two into my manual boxes too. Now my manual boxes LOVE the Torco SGO synthetic 75W-140 oil. There the syn oils shine. Beware of heavily advertised oils that have become popular despite being poor lubricants. Quality is inversely proportional to advertising.

This section claims that this specific oil, and this oil only, will nearly reduce friction in an engine to zero! Besides noting that this is impossible, this claim should be looked at skeptically as it sounds like more of a promotion of this company’s product (phone numbers included!) than a scientific study of engine lubrication. The article calls 5w20 and 5w30 oils grinding compounds, which probably reflects the view that auto manufacturers are designing engines that grind themselves to dust in order to jack up repair costs. But if these oils were so dangerous why would many new cars be moving to 5w20 as a standard oil viscosity and still offering standard warranties on their products? I worked in an automotive shop for a period of time (albeit short) and of the hundreds of cars that came in none, no matter how old, had catastrophic engine failure, serious oil consumption issues, or anything else that could be attributed to dangerously thin oils. Though the article recommends thicker oils than the manufacturer, it certainly does not make as good a case as every major auto manufacturer (no case at all, in fact, besides the fact that the author’s transmission “LOVE”s the Torco oil).

5. Have your trusted mechanic run your sensors on his expensive computer monitor that checks the status on all your car’s computer settings, sensors, catcon and perform diagnostics on them. This is a good thing to do anytime but essential after tuning the engine or making significant changes. But do NOT disconnect your battery if you are already getting good mileage. You will lose all the settings in the computer such as the spark timing history. It is okay to throw away bad settings, but not good ones. You might be surprised what this will show. The condition of your oxygen sensors is the most critical item to look at regarding mileage, even if they are somewhat new.

Having used said computers in a shop environment, I can say that there is not much reason to spend the money to take your car into a shop unless there is a reason to suspect there is a problem. It is true, however, that certain cars can learn ignition and fuel conditions based on storing driving information. That said, I have never personally experienced any noticable drivability or FE hits due to unhooking my battery (though I have noticed my safety from not working with live wiring). This feature is something that needs to be checked on with each individual car, so do some research on your own vehicle before jumping to any conclusions.

6. Use NGK V-Power spark plugs because they have a proper resistance level that will not short out the high voltage secondary during moist or very cold weather. Avoid platinum or palladium plugs. Other plugs (Champion or AC) have excessive resistance that wastes spark energy. Set the gap to .030 for best results for most cars. Too wide a gap causes a needless waste of amperage. The milliamps actually fire the mixture rather than the voltage. AMPS = HEAT. You cannot believe all the popular hype about VOLTAGE. But be certain your plug wires or cables are perfect. I now use the superb Kiker Wires for mileage. Replace your cables if they are over five years old. NGK also makes excellent plug wires. Bad cables will cause missing and poor MPG. Some plugs that come set at .060 can be reduced to .035. You may wish to contact PatKiker@yahoo.com for the best possible spark plug wires that will add MPG to your car or truck. We proved they work. See www.KikerPerformance.com.

Firstly, not the blatant product advertising in this tip.

Now, on to the technical aspects of this point. Modern ignition systems have had decades of work put into them and are extremely reliable. According to one article, almost 99% reliable. Given this, there is little that can be improved in terms of spark reliability. Plug gap, style, and composition are much argued over, though there is no conclusive data that I have seen pointing to any particular type of plug. I will admit that I have experimented with side-gapping, which I will detail on the site, but honestly, aside from indexing (which I will also write an article on) there has not been enough data to support any specific plug configuration outside of stock. In regards to the product being adveristed by this point, Kiker Plug Wires, even the company’s website has little to say in its own defense. There have been many dynamometer spark plug and wire comparisons over the year, and none of the credible studies have shown more than a few HP difference (consider these tests are generally done on high rpm, high horsepower engines that demand much more of their ignition systems and the average fuel economy driver).

7. Install new oil filter, air filter and fuel filter from Baldwin Filters or Donaldson Filters because they appear to have the very finest filters (fiberglass material) available anywhere for cars, trucks and luxury cars. Cleaner oil certainly delivers better mileage. Baldwin Filters are available from any Peterbilt Truck shop. We also use Donaldson filters #P551300 in a wide number of cars such as Toyota, Ford, Chrysler and Mazda products with the 3/4×16 thread size. Look in the catalog for the biggest Baldwin or Donaldson filter that will fit your engine having the same thread dimensions. We get our Donaldson filters from Hydraulic Specialty (Dave) at 763-571-3072.

While this may or may not be true, the article gives no proof supporting its endorsement. Here again it seems more like a case of third-party advertising than a legitimate fuel economy claim.

8. Avoid ordinary oil labeled with the latest API specs of SJ or SL. These have very low additive content. Use motorcycle oil with the old specs of SF, SG or SH for better additive content. It happens that motorcycle oils and diesel oils are exempt from the newest changes that reduce the important additive content.

According to the American Petroleum Institute: “For automotive gasoline engines, the latest engine oil service category includes the performance properties of each earlier category. If an automotive owner’s manual calls for an API SJ or SL oil, an API SM oil will provide full protection.”

9. Use larger than standard tires. I usually drive on one-size bigger tires. This is better in winter and normally yields better mileage all year around. Yokohama tires give great traction in winter. My Neon had bad traction until I bought these tires plus they are nice and quiet. A slightly higher tire pressure may also help mileage.

Taller than standard tires will lower your effective final drive gear ratio, which is better for gas mileage as less revs = less fuel burnt. It would be nice of the article explained this, but at least it has the information correct. Properly inflated tires improve mileage over poorly inflated tires (source), and overinflated tires improve mileage over properly inflated tires (article to come).

10. Replace your thermostat with a new one that is 195 degrees because a hotter engine has better efficiency and lasts longer. NEVER use a cold thermostat setting. The good additives in the oil are not triggered unless the oil reaches the proper running temperature. This will boost your mileage for sure due to improved Thermal Efficiency with a warmer coolant temperature. Your ScanGauge can reveal your exact engine coolant temperature. Thermal Efficiency is the most critical element of an engine.

Here, again, this article seems to be in line with good sense about improving mileage. The modification won’t do much, probably won’t even be noticable, but I believe it works. Consider this graph displaying fuel correction values based on engine coolant temperature in hondas:

You can see my article for more information on this modification.

11. Perhaps you still have a carburetor or you own a beautiful antique automobile. I often soldered or plugged the power value shut in many kinds of carburetors to prevent enriching the fuel mixture unnecessarily. Sometimes the carbs flooded frequently until this fix. Especially when I ran multiple carb combinations. The problem was the power value picked up vibrations from the engine and opened when it was supposed to stay closed. This killed mileage and wasted lots of gas. The plugs would come out black with soot. So please do this. You will not even notice anything except smoother operation and a lower gas expense with improved mileage.

I honestly have no qualification to evaluate the performance of carbs in such a situation. If someone in the know would like to give me an email they should feel free to.

12. Watch carefully for signs on the gas pumps warning the fuel contains alcohol. Ten-percent ethanol is common but not all stations contain that much. Not all stations carry a sign on their pumps. Some only have 3 or 5-percent to keep their customers happy regardless of the laws. Some have none. But the ones that warn you of ten-percent or HIGHER–go somewhere else. And test all the stations in your area to be sure and use the best one. We like Cenex stations because they often have 87-octane gas without ethanol. Stations certainly vary a lot. In general, the less alcohol, the better your MPG. Remember all gasoline is different.

This is true. Ethanol has a lower energy content than regular gas and will yield less mileage, though it’s use is justified in many senses.

13. Good gas might be obtained  from Cenex or Texaco or Chevron stations or from Wal-Mart stations in your area. But all stations have different gas. So test them all. For example a Shell station near me used to have the best gasoline in the Twin Cities area. But the ethanol content has picked up too much water and now makes my cars buck and jump. So I went to Cenex. In Sioux Falls, the best gasoline is from the Cenex and Wal-Mart stations. In California, the best gas comes from Chevron stations. Now I go to Hudson, Wisconsin for Cenex gas without ethanol. Most stations in the country do not usually sell high mileage gasoline. Watch out for high alcohol content. Avoid ethanol. You always should test the gas because there is no way to be sure except by careful and consistent MPG testing. You cannot mix gasolines and be sure of results. It takes about four tanks of ONE type of fuel to gain accurate results. We like Cenex gasoline in Wisconsin because it does NOT contain alcohol and MPG is a healthy 30-percent better than gas in Minnesota. For the past five years these stations have given me bad or poor mileage in my cars: Some Phillips 66, Shell, all SA, Marathon, Ashland and Holiday (BluePlanet in particular)–apparently due to high ethanol content. My 1986 GMC died 20 miles after my son inadvertently filled it with BluePlanet. The new fuel tank (only two weeks old) had to be removed and cleaned out. The fuel filter was replaced and the gas lines blown out. Only after this work and putting in Texaco gasoline, did the car run again. The trouble with ethanol is it attracts water and water acts like a fire extinguisher in the combustion chamber. Not to mention the rust and corrosion problems alcohol causes in outboards and snow blowers. Ethanol is forbidden in aircraft engines. If some moron tells you water should be run with your gasoline, walk away. Plus ethanol has a much lower BTU content than straight gasoline. We need high BTU content for good economy. A recent report praising ethanol from the U.S. Senate is dead wrong. It is propaganda. Anyone who has a ScanGauge in the car knows the truth.

There are several clues here as to why this gas prejudice does not make sense. In this case his brand affliation seems slightly more justified than at other points during the article, so that facet ought not be a main feature of this analysis.

Firstly, great attention should be paid to the two examples he cites against gas with ethanol. In the first such case the author states that ethanol from the Twin Cities area makes his cars “buck and jump.” Logically, could dozens of companies put gasoline in thousands of stations that made cars buck and jump? If too many peoples’ vehicles began bucking like broncos surely someone besides this author would have noticed. His second example is as follows: “My 1986 GMC died 20 miles after my son inadvertently filled it with BluePlanet. The new fuel tank (only two weeks old) had to be removed and cleaned out. The fuel filter was replaced and the gas lines blown out. Only after this work and putting in Texaco gasoline, did the car run again.” Forgive the attempt at humor, but the roads must be constantly clogged around that gas station from all the cars that get their gas their spontaneously dying. Besides these rather far-fetched claims about gas station differences, this article claims a 30% difference between E10 and regular gasoline. A gallon of gasoline has ~125K BTUs of energy and E10 has ~120K BTUs. Maybe the text book industry has taught me crooked math in order to enlarge profits, but it seems to me that E10 has about 4% less energy than regular gasoline, certainly not 30%! But, then again, the Senate did cook all those faulty documents on ethanol.

14. There is a great little device available to check your exact gas mileage, gas quality and more. See  ScanGauge.com for a very timely instrument that fits most cars 1995 or newer. It works with gasoline or diesel. My 1995 Neon has one and I often see average readings above 60 MPG. Recently above 63. My 1995 Mazda has one and the best MPG on that pickup was 41 coming back from Canada on gas without ethanol. It is common now with acetone and xylene in my Mazda (Ford Ranger) to see 32-33 MPG. So you get to see your real-time MPG, inlet temperature, water temp and many more details as you drive. This inexpensive tool (for gas or diesel) should end a lot of debate over what works for mileage and what does not. A steady 50 MPH offers the best average MPG test range on the TRIP setting. But MPG is only one of the data the ScanGauge can tell you about your engine performance on either gasoline or diesel fuel..We test gas stations with only two gallons of gas per station and record the findings.

I will not debate the usefulness of this device. I will however state that 50MPH is not the ideal speed (and offer proof, in an article to come), that this device does not make you an expert, and that it cannot be used to accurately test gasolines two gallons at a time. Instantaneous fuel economy feedback is the single most important piece of getting good gas mileage, and will be dicussed at length in its own article.

15. Empty your car’s trunk. Some people carry hundreds of pounds of junk in the trunk out of convenience. All that weight is costing you a fortune week after week. Put it someplace else. Save yourself from wasting fuel. It’s harder on your transmission and engine to carry it around needlessly.

Extra weights lowers fuel economy, but only by a very small percentage that can be easily removed. Unless you’re carrying several corpses in your trunk it is doubtful you are losing a “fortune” to excess weight.

16. Bump your engine timing by five or ten degrees if you can. This brings a BIG improvement to power and economy. You MPG will go up and the car will start easier and run better. The factory timing is deliberately late in nearly all engines. Your car computer needs a tool like an NGS StarTester to alter the timing. This tool is a Ford item from Rotunda. This trick WILL improve emissions as well as mileage because any improvement to MPG will reduce total emissions as well. We are further working to allow changes be made easily to car computers via a laptop and will reveal that info to the public soon.

The ability to alter ignition timing at the ecu is very limited to most people. It is perhaps easiest with hondas, and I have done so on my car. Even 3 degrees of ignition advance over stock led to knocking throughout the RPM range and gave no noticable increase in power. Perhaps more poorly designed engines can benefit from ignition advance but it should not be done blindly with the expectation of results. A few horsepower at the peak of the range might be noticable after dyno tuning with a professional (on a stock to lightly modified vehicle).

17. There is talk about whether we get better MPG with a tank that is filled when it gets half empty versus when it gets near empty and needs to refill. Keeping the tank more full prevents air from entering into the tank space. The less air in the tank is good for one main reason. It reduces the water in the air from getting into the gas. The fuel filter may need to be changed if you notice a difference. The fuel pump is more efficient when the tank is full. I have done it both ways for long periods. I usually refill when my tank is half empty. It costs less too. And acetone always makes the water content in the gasoline less noticeable in terms of smoother running and better MPG.

Yet again this article comes back to its preoccupation with water in the gasoline. How much water could possibly come from a few gallons of air in the tank. Compare this to the incomprehensible amount of air that is sucked through the intake on a daily basis. What is a very small amount of water vapor in the gas tank compared to a humid or rainy day?

18. We suggest keeping a new fuel filter in your car. If the fuel filter is more that five years old, buy a new one. A slightly plugged filter will affect the mixture and usually lowers the MPG. A full tank has a higher head and makes the job of the fuel pump easier. Let an expert do this job. Fuel filters need to be changed about every 15 to 25,000 miles but people drive much longer that that before the poor filter gets replaced.

A clogged filter is a problem. If it’s clogged, replace it. However, I am driving my CRX with over 128k on the stock fuel filter and I am not motivated to replace it. Perhaps I’m just that cheap, but as long as I have no fueling issues to suggest that it is severely clogged, it will remain where it is.

19. To seal maximum warmth inside the oxygen sensor, insulation in the form of Reynolds Aluminum Foil is employed with several layers to insulate the oxygen sensor. Do not remove the sensor. Then we repeat the process several more times per each sensor. The sensor up on the exhaust manifold is ignored as it may be too difficult to access. Finally we use .030″ copper wire to wind around the aluminum foil about one-inch apart to keep it from blowing away. The goal is to fool the car’s computer into sensing too warm a sensor so it adjusts with a slightly leaner mixture and possibly a slight advance in timing. The end result is smoother engine operation and better MPG. This trick is especially important in severe winter climates. We no longer use insulating tape around the aluminum foil.

Oxygen sensors work by measuring the amount of oxygen left in the exhaust gasses. They are not operational until reaching a certain temperature, but once at that temperature their measurements are based on a chemical reaction of the exhaust gasses with the sensing element. Insulating the sensor could only possibly make the process of warming take longer (as insulation resists change in temperature). (source)

20  The car computer system reads engine vacuum and the throttle position sensor as you drive. The less you depress the throttle, the less fuel is sent to the injectors. The higher your manifold vacuum, the less fuel is received by the engine. The computer also controls the air-fuel mixture ratio. When you have a ScanGauge on your car, you soon see that backing off the accelerator while going down a slight hill sends the ScanGauge an immediate reading over 100 MPG. Of course this is averaged over a longer distance into the overall reading on trip setting. But the immediate reading shows a huge MPG reading during this condition and that reading is averaged into the average. This implies that frequent coasting is good for MPG. Do not put the car into neutral. Just try to keep your foot off the accelerator as much as you can and still maintain a reasonable speed. Make it a habit. It helps to have a vacuum gauge on your dash. I once saw a 427 Chevy engine with a large one-barrel truck carburetor go from 9 MPG to 28 MPG because the big Chevy V-8 had lots of vacuum at part throttle to break up the fuel particles and achieve full vaporization and excellent combustion.

This description of efficient driving methods is largely worthless. Backing off the throttle does increase mileage, but there is much more to it. The author is for some reason biased against neutral coasting, but does not explain why. Coasting is one of the most important techniques to achieve high mileage. Fuel efficient driving techniques are much too much to talk about in a single paragraph, or even article, but I will post articles on different techniques as I find the time to write them. Driving technique is the source of the singlest largest fuel economy gain in any car (barring major modification to engine, transmission, or body).

21. The use of Kiker Wires is a great improvement to a car’s ignition. These spark plug cables are different from anything else out there. MPG keeps going up. Power is improved too. Call Pat Kiker at (863) 453-4942. PatKiker@yahoo.com.or www.kikerperformance.com. Read the article Approaching Footsteps. Kiker Performance is coming out with a battery connection that is really amazing.

Once again, the mysterious Kiker wires are advertised. But where is the proof, the testing, or the sound theory?

22. The Fog Warmer from BrightGreen Inc.is a wonderful device to boost mileage perhaps 5-11 MPG. Performance is up too. Call if you are serious about getting one of these that attaches to the upper radiator hose on your engine. 612-345-5085 or write for info to milespergallon@gmail.com soon. The address to order is BrightGreen at POB 18797 in Minneapolis MN 55418. The cost is $137 plus $9 for shipping. Checks only for now. What is your engine size? Instructions and photos are at www.brightgreen.us/install.htm and at www.brightgreen.us/photo.htm for your convenience.

This point, the last of the list, seems most like an advertisment. It hardly describes the product; does little more than attempt to sell it!

I’m no expert. I’m no insider. I’m no prophet. However, something gives me the feeling that if I slipped the author a $50 I could get him to publish glowing support of whatever product I felt like pawning off on the unsuspecting public.

Have you ever hated the look of your radio antenna? Or maybe been bothered by all the aerodynamic drag? I have. Solution: It’s gone!

Purpose: To cut down on aerodynamic drag and improve the look of the car.

Time: 15 minutes

Tools:
- Flathead Screwdriver

Supplies:
- Block Off Plate
- Gasket
- Reused Screws

You can get this stuff at the local dealership or online (cheaper) at one of these places.

Here’s the antenna. Undo the two screws and yank it out. Make sure to unplug the other end from the stereo.

Awful picture of the antenna on the ground:

The left over hole:

The two parts, I spent about 10 bucks on both:

Put them on with the old screws:

Admire your work:

The CRX no longer looks like an RC car! Quick and easy (mehbe not too important) but it was certainly worth it to me.

The front grill block is on of the quickest, easiest, and cheapest ways to cut down on aerodynamic drag in your vehicle. While it doesn’t amount to much, it does make a difference, especially considering that a large amount of aerodynamic drag is caused by this opening. It’s best to leave it only partially blocked so that the radiator recieves some airflow, however, a large block is okay because radiators are typically larger than they need to be, and fuel economy drivers tend not to abuse their engines too heavily.

Many new cars, including certain Mercedes and Hondas use electronically controlled radiator shields that open/close depends on engine cooling requirements. Take a look at this Civic for an idea what this looks like:

Purpose: To prevent air from entering the grill to reduce drag as it moves through the radiator and engine bay.

Time: 1-3 hours depending on complexity of project

Tools:
- Hobby Knife
- Hot Glue Gun

Supplies:
- Coroplast
- Spray Paint
- Foam (for modeling)

I chose to repaint the trim on my bumper as well as do the grill block at the same time, so first I removed the bumper. If you leave it on you can get it done much more quickly, but that’s up to you. Just follow my mounting instructions with the bumper on the car.
Click here to see how to remove your bumper (as shown in the wire tuck page).
This is my bumper removed, you can see the grill opening as well as the two pockets on the side. The side pockets are not supposed to cause much drag but I covered them anyway just to smooth thing out as much as possible:

Here’s another shot to get an idea of the bumper’s geography:
I used this style of insulation foam to make templates because it is easy to work with:
One of the templates sitting in a side pocket:
I then transfered the template to the coroplast, cut some support to place down the side of the pocket to mount the coroplast to, and cut off part of the coroplast towards the center of the bumper so it would mount flush to the bumper where it tapers together:
The center pieces are just glued to the ribbing on the grill and then glued around the edges from behind:
I taped up all the painted portions of the bumper so I could respray the trim and the coroplast black:
A shot of the finished product remounted:

I think it turned out pretty darn good,

One of the things many car owners dream of is a cleaner, more simple engine bay. It seems like an impossible task; what does one do with all that stuff? There are a few solutions that are simpler than you may imagine. I begin working on this task in the form of a wire tuck and hope to give some guidance as others go through this process. At the same time other things will be tucked or cleaned up, but the main objective at the moment is wiring.

Purpose: To be honest, there is no purpose to this beyond cosmetics. Some make the argument that you are better able to service your wiring when it is where you want it, but I’m not sold on this. I do, however, know that I am much more familiar with my car’s wiring and wiring itself. It was well worth the effort.

Time: Yikes! It depends on how much you do, and how thoroughly you do it. It took me a few days while being patient and thorough (not entirely full days either).

Tools:
- Automatic Wire Strippers
- Soldering Pen
- Lighter (to shrink the shrink wrap)

Supplies:

- 200 foot of stranded wire, various sizes. Just take a look at some of the wires and you’ll get an idea what you need
- Solder, I’ve had a pound spool I’ve used over and over again
- Shrink wrap, various sizes but mainly 12-20 ga.
- Electrical tape

Before shot, it’s hideous:

Diagrams of the two round shock mount plugs, make sure to label the identically colored wires!




This is what headlight wiring looks like, one of the main tasks will be to relocate these wires to the fender brace so they will be out of the way:

Now we’ll begin with taking the body panels off so we can relocate the wiring.
Take your corner light out:

T-bar comes out to help remove the bumper, it has 4 10mm bolts up top, on on the bottom, and the hood pop cable is clipped to it:

Those little screws were rusted in badly so I had to take them out with the vice grips:

Also on the bumper there are two 10mm bolts on the bottom and two screws on each side in the wheel well. Also, there are two screws under the corner light. Once that’s all off slide the bumper off:

The headlight wiring will be tucked down through the support brace for the fender. To get the fender off there are 3 10mm bolts on the top, two in the front corner, two under the door/drim area at the bottom and one on the top behind the door. Get at these with a wrench from the side with the door open so you don’t damage your paint. You’ll also need to detach the wheel well plastic from the body of the car, just undo the plastic screws or slide the plastic around them.

I lost the picture, sorry!
Unplug everything. You’ll need to take off the horn to get the plug off, but it’s only one 12mm bolt:

Yank the headlight harness out the side there so you’ve got it all acessible:

Oh no, look at those plugs. Two go to the windsheild washer nozzles. I took out the reservoir and the lines, but if you wanted to you could leave the reservior (or move/modify it) and tuck the lines in the fender brace. At this point you basically just cut the plugs off, label all the wires (as you cut them off), and pull the wiring inside the cabin so you can put it out the side:

Side of the car where the tucked headlight wiring will come out and go into the fender brace:

Cut open the harness so you can start cutting plugs and labeling the ground wires. The annoying thing here is that some wires go into the cabin and some go to the multiground. I just cut the cabin wires and tucked one at a time while labeling the wiring on the multiground:

Pull this little plug out. Through the hole the wiring will come out of the cabin of the car. When you cut a wire you pull it through from under the dash and shove it out the side here:

The hole it comes out of in the middle and where it goes in the very top-right:

Opened harness from the engine bay, all these wires will be gone besides the two to the master cylinder:

The harness from the inside:

Cut the first plug, pull the wire through, shove it out, and realize you’ve started:

First wire is wrapped around and through the fender brace:

Comes out through this little hole here:

There’s a multiground for each side, make sure to label the wires just because. Iono if it matters but labeling is very important just in case!

Everything cut off the multiground and labeled up:

The multiground tucked into the corner bumper/fender area:

Look at all the wires coming together:

Crappy shot of all the individual plug wires taped together:

All the wires on the passenger side that go through the fender. The black wires are all for the wiper motor:

You can see where the wiper wiring goes into the fender now:

Cut open the wiring for the injectors and run it up from the bottom under the IM runners:

Turned the brake booster vacuum hose around to take advantage of its natural bends and cut some off on the unbent side. Don’t forget to flip the one-way valve if you do it like I did:

Better look at the driverside wiring all done up:

Almost every wire going in through the old VSS cable hole, damn it was getting cramped after a while, this was really a pain, but worth it I think:

The two MC wires going through that driver side firewall opening:

Passenger side multiground and relay down where the intake resonator used to be:

Fusebox: Really no pictures needed, everything screws off/unplugs besides the power wire to the battery, which you need to lengthen X amount depending on where your battery is and how you’re routing the wire. This was the easiest part, by far.

Finished product: