Fuel Economy: Busting the Myths

Brian Glastetter
March 30, 2011

During my many years of working at a dealership service department, one trend I have observed is that whenever fuel prices go up, complaints about fuel economy also go up. The recent rise in fuel prices has also driven up sales of air filters, spark plugs, and routine maintenance.

I must admit, OPEC is certainly getting more of my money these days. Twenty-two years ago, when my trusty Ford Ranger, affectionately named Betsy, was new, the fuel tank took less than 12 dollars to fill. Now, after a recent fill up, Betsy consumed 63 dollars worth—$63! My income has certainly not increased five times over the same period. The shock to my wallet makes me want to shriek.
There are a lot of tips, gadgets, and articles out there promising better fuel economy, but which ones actually work? I examined several of the more common and infamous fuel economy tips and have separated the myths from the realities.

Computer Chips and Programmers
Automobile manufacturers employ some of the best and brightest engineers and have billions of dollars dedicated to research and development. One fuel-saving device the industry has developed is the computer chip or programmer. To save on fuel, a programmer can be downloaded into a vehicle’s electronic engine control system. It will “lean” the fuel system during cruise in order to increase fuel economy. But like Newton’s Law of Physics, anytime an action occurs, an equal, but opposite reaction takes place. Though this programmer may help your fuel economy, it can also cause potential long-term damage to the engine’s valves or pistons. Many of these chips and programmers work well at increasing fuel economy, but have little regard for durability or emission requirements.

—Not recommended

Using Air Conditioning
Operating the vehicle’s A/C system can reduce fuel mileage by 1 to 2mpg. Using the vehicle’s vent system to cool the vehicle can be efficient, but it’s not very effective. Due to the drag it creates, driving with the windows open can actually consume more fuel than running the air-conditioner. Modern vehicles are now utilizing an electric motor to power the A/C compressor, so no fuel mileage will be sacrificed.


Drafting Behind a Large Truck
Unless you are a regular driver on the NASCAR circuit at Talladega drafting behind Mark Martin, it is not advisable or safe to stay too close behind a large truck and it doesn’t make much of a difference in fuel economy.

—Not recommended

Driving the Speed Limit
Test results indicate a loss of about 2.4mpg for every 10mph increase above 40mph due to increased wind resistance. The tortoise and the hare fable appears to be true after all.


Installing High Flow Intake and Exhaust Systems
High flow intake and exhaust systems increase an engine’s volumetric efficiency (the breathing of the engine). These product manufacturers claim incredible fuel economy results, but independent testing frequently shows only nominal increases in power and fuel economy. Sometimes, the cost of these products outweighs the actual realized fuel economy increase. Additionally, surveys show that people who install a loud, free flowing exhaust system usually drive more aggressively.

—50/50 Recommended

Buying a Small, Fuel-Efficient Car
Replacing a vehicle with one that is 10mpg more efficient can save over $1000 a year (though this estimate certainly increases with the rising fuel costs). However, before you buy, you should do the math. If the newly acquired car payments do not offset the fuel economy and savings, then a new vehicle probably will not be worthwhile.

—Recommended (only if the math adds up in favor of fuel savings)

Planning and Combining Trips
Carefully plan your trips and driving routes so you can avoid traffic congestion. Combine as many errands as possible to keep the miles you drive to a minimum. Of course, the best fuel economy is not driving at all. Walking, biking, or just car-pooling with a friend or neighbor yields great savings on the fuel bill.


Interestingly, many fuel-saving tips are directly related to how you actually drive. The most notorious fuel economy culprit is your right foot on the accelerator pedal. Aggressive driving can also drastically reduce the fuel economy on even the most fuel-efficient vehicles. Pay attention to the way you drive—just like a diet, every little bit helps.


Brian Glastetter

About the Author

I am a 21+ year Senior Master Technician and a Master ASE technician at a Ford dealership. I take pride knowing that I deliver a quality repair with honesty and integrity.

1 User Comment

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By , July 04, 2011
I would recommend using Marvel Mystery Oil additive to your gas or diesel. This helps keep your valves and injectors clean. It is also an oil additive which prevents your oil from breaking down and keeps the top part of the cylinder lubricated. I helps stop valve clicking noises. Marvel mystery is also sensational for lubricating air tools. We had an air dual action sander that wasn't working and when we poured marvel mystery oil into the air inlet is started working to the point that it sounded as good as new.