For better mileage, adjust the nut behind the wheel

The price of gasoline has dropped 7.4 cents in the last week, to an average of $3.66 a gallon, but most of us aren't feeling much richer, especially when we rely on our cars to get to work or as part of our work.

People who study gas mileage know one of the easiest ways to improve it is to adjust the nut behind the steering wheel.

The University of California, Riverside's Center for Environmental Research and Technology think they have a way to boost fuel efficiency by as much as 30 percent without touching the car.

With a $1.2 million federal government grant (naturally), they're finding ways to give drivers positive feedback when they drive in ways that save gasoline without being annoying. That might use network connectivity, GPS and infotainment systems -- making "hypermiling" a game for drivers who grew up on videogames.

You may have already experienced similar ideas driving a hybrid vehicle that grows green leaves when you're gently cruising down the highway and drops them off when you jam on the gas pedal.

One company's car will save vehicle diagnostic data on a USB drive that can be used to generate a report on your computer that analyzes CO2 emissions and fuel consumption, and compare your driving style to other owners.

What drivers don't like is a car that nags them, like one system that made it harder to press the accelerator pedal far enough to waste fuel.

But we think the prospect of saving money for driving sensibly and losing money by driving poorly should be enough incentive.

The U.S. Department of Energy offers these tips at fueleconomy.com:

* Drive sensibly. Rapid acceleration and braking wastes gas. It can lower your gas mileage by 33 percent at highway speeds and 5 percent around town.

* Observe the speed limit. Gas mileage usually decreases rapidly at speeds above 60 mph. You can assume that each 5 p.m. you drive over 60 is like paying an additional .29 cents per gallon.

* Avoid carrying unnecessary, heavy items in your vehicle. Depending on the size of your car, each extra 100 pounds can reduce your miles per gallon by 2 percent.

* Avoid excessive idling, which can use a quarter to half gallon of fuel per hour, depending on engine size and air conditioner use. It only takes a few seconds worth of fuel to restart your vehicle.

* Use cruise control, except in very hilly or slick conditions.

* Use overdrive gears, which cause your car's engine speed to lower, saving gas and reducing engine wear.

* Keep your engine tuned up, which can increase mileage as much as 40 percent, depending on needed repairs.

* Keep tires properly inflated, which can improve your mileage up to 3.3 percent.

* Use the recommended grade of oil.

Surprisingly, according to new information, replacing a clogged air filter on a modern, fuel-injected, computer controlled gasoline engine does not improve fuel economy, but it can improve acceleration time by about 6 to 11 percent. It still helps fuel mileage on older, carbureted engines.