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How you drive can affect your gas mileage


We all like to race stoplight to stoplight, it’s a guy thing. But, did you know that nothing can affect your gas mileage more than your driving style? Studies have shown that you can save up to 33% on gas by altering your driving style.

Before we get into how you should drive for the best gas mileage, let’s talk about what you should do before you leave the driveway. The first thing you should do, if it’s hot outside, is turn off you’re A/C and roll down the windows. This will reduce the load on your engine, and clear out the super heated air that has built up in your vehicle. Once you are above 45 mph, roll up the windows and turn on the A/C.

We can now start our discussion on driving style and discover how you can save up to 33% on gas. The first thing to think about when driving is conservation of momentum. Consider the following two scenarios…

1. You are driving along at 45 mph and see a red light ahead. You wait until the last second and slam on the brakes, then accelerate away when the light turns green.
2. You are driving along at 45 mph and see a red light ahead. You let off the gas pedal, and coast into the light, while anticipating when it will turn green. If you time it right, you never stop and continue on your way, ahead of where you would have been in scenario #1

This type of thinking in scenario #2 will put money back into your pocket. Your brake pedal is your enemy when trying to get better gas mileage. If you can anticipate traffic ahead of you, and avoid having to push on the gas pedal hard, you will save gas. Any time you use the brakes, you are losing momentum and wasting energy.

I had a friend in high school, whose dad put a vacuum gauge in all of his vehicles. A vacuum gauge in simple terms, measures the load on an engine. It served to remind my friend’s dad how he was driving, and forced him to go easy on the gas pedal to save gas. Consider having your mechanic install one of these gauges, the cost is minimal, and you may learn a little about how you are driving. If you have a newer car with an advance engine computer, it may tell you your instant and average mileage. Use the instant gas mileage readout instead of a vacuum gauge, it’s just as good.

You want to accelerate as mildly and evenly as possible to get to your desired speed. If you have a tachometer in your car, you can watch engine RPM and try to keep it under 3,000. You should be able to get to your destination in a safe and speedy manner, using these techniques and save some gas in the process.

There has been a lot of debate about what is the best speed to drive on the highway. Politics and safety issues have clouded the issue even further. The fact is that every car has it’s own speed where peak efficiency occurs. I had a Corvette that got the best gas mileage at 70 mph. It’s not practical to drive this fast everywhere, so I compromised and kept it legal as often as possible. Depending on your engine, transmission and gear ratio in the axle of your car, you ideal speed will be higher or lower than my car. The most important fact to remember is to keep your speed steady and avoid abrupt stops and starts.

I have heard various automotive journalist report better gas mileage by not using the cruise control. There reasoning was that they were focused on driving for efficiency and could make better decisions that the cars cruise control computer. This theory is valid, if you are on a highway with a lot of elevation changes. If you are not using cruise control, you can allow your vehicle to coast down long hills and build up some extra speed, which will help you climb the next hill. Of course you need to use some common sense here and not allow your car to go too fast to avoid speeding tickets or dangerous driving conditions.

The last tip I can offer on driving, is make your vehicle as light as possible. The lighter your vehicle, the less you engine has to work to move you around. Remove any unnecessary items from the trunk and car to help keep your car as light as possible.

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Posted: 2nd June 2006  |  Author: Kevin Schappell  |  Category: Car Care, Fuel

2 Responses to “How you drive can affect your gas mileage”

  1. jackjack says:

    I was wondering how to calculate the peak efficiency speed for any car.

  2. waltr34 says:

    I once rec’d with my Insurance bill some info stating the peak speed for mpg was 45mph. Because of the resistance of the air against the body of the car itself. My own test with my ’04 Honda Civic 2dr & ’98 Chevy G3500 box truck had these results. At 65mph the Civic got 34mpg & the Chevy truck got 10mpg. At 55mph the Civic got 40-41 & Chevy truck got 12-14.
    I haven’t got this better mileage over the winter due to I think the winter blend of gas & the air being denser when its cold. Anyway it comes to almost 20% better mileage doing 55 vs 65.
    I wonder if mythbusters or someone could take a sq. ft. of some lightweight mat’l glue it to a digital scale & attach it to the front of a car to find out how much air resistance there is per sq. ft. at a given speed. Also for automatics with a tachometer, jot down when the trans shifts into the next gear & the rpms drop on the tach. Less rpms = less gas used. If your car shifts to the next gear 3mph below the speed limit set the cruise there & save.

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