It's easy to squeeze a few more miles from a gallon of gas

Dollar bill sticking out of gas tank

We play a central role in our car's fuel economy.

There is a human element in fuel economy -- a very significant human element as a matter of fact.

In this age of avoiding responsibility, it may be tough to hear that our behavior and indifference affects the fuel economy of the vehicles we drive.

Researching an assignment, I stumbled across a media release of fuel-saving tips issued by Chevrolet.

I'm not one to get all caught up in the "greening of America," but it makes sense to do what you can where you can, especially if it saves a little coin.

We've heard many of these tips -- such as under-inflated tires reduce fuel economy -- for years. However, what I found interesting in the Chevy list was that many of the tips actually had numerical values attached.

GM fuel-economy expert Roger Clark told me that, in general, operating any system in a car makes the engine work harder and affects fuel economy to some degree. "Anything that uses energy burns gas," he said.

Here are some of the specific tips I found most interesting. The numbers are as reported by Chevrolet, but include some results from EPA testing.

Don't ignore the service-engine light. Even if the car seems to be running OK, there's a problem and that problem is likely reducing your fuel economy. A properly tuned engine can improve fuel economy by 4%. Fixing an ailing engine component, such as a faulty oxygen sensor, can boost mileage by as much as 40%.

Check your tire pressure weekly with a pressure gauge. Under-inflated tires can lower fuel economy by 0.3% for every one-pound-per-square-inch drop in pressure of all four tires.

Be a smooth operator. Rapid acceleration and hard braking can lower gas mileage by 33% on the highway and 5% in city driving.

In town, roll 'em down. At speeds below 40 miles per hour, you can increase fuel efficiency by as much as 10% by turning off the air conditioning and rolling down your windows. Above 45 m.p.h., wind drag burns more fuel than the AC.

Slow down. Every 5 m.p.h. above 60 m.p.h. is the same as adding an additional 24 cents to the cost of a gallon of gas.

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