How you drive and how well you take care of your car affects how much gas you use.

With the U.S. Energy Information Administration forecasting gasoline costing an average of $3.92 per gallon from April through September, people looking to maximize their mileage have options, automotive experts say.

Car maintenance and driving styles are areas where drivers can look for savings, says Dick Rogers, automotive technology professor at Lincoln Land Community College in Springfield, Ill.

“There are so many factors that enter into why we are using so much fuel. The majority of the time it’s either improper maintenance to the vehicle, improper inflation on the tires or it’s just our driving styles that we have,” Rogers says.

Rogers and Brandon Kimbro, automotive technology instructor at Capital Area Career Center in Springfield, offer tips on how to maximize gas mileage.

MAINTENANCE

Take your vehicle for a tuneup: Periodic tuneups — including a change of spark plugs — according to manufacturers’ specifications are a major way people can save on fuel, Rogers says.

“The fuels, the oil, the transmission fluid, the coolant ... power steering fluids should be changed doing those service intervals, too, along with the filters,” Rogers says.

“As those fluids get old, then the oil, the viscosity increases a little bit and the engine’s going to have to work a little harder, so it’s going to take a little bit more fuel to make that engine work a little harder.”

Not changing the coolant in the radiator could cause the engine to overheat, and in turn to overwork, Rogers says.

Check and correct tire pressure weekly: Driving with underinflated tires requires the engine to work harder and use more gas. A tire pressure gauge can help you determine if there’s enough air in the tires.

“That’s an item that is really overlooked,” Rogers says. “Most people, they don’t even know what a tire pressure gauge is.”

Rogers suggests people buy tire pressure gauges (available in most auto parts stores for $3 to $5) and learn how to use them. Most cars have the recommended PSI — pounds per square inch — of air listed in the owner’s manual or on a sticker on the driver’s side door jamb. Most service stations have an air compressor so you can inflate your tires if you’re a little low.

“It used to be that 32 (pounds per square inch) was about the standard. Now you’re seeing that it’s usually up about 36 psi is the standard,” Kimbro says. “They’ve just increased the pressure, which is going help reduce the resistance, help (the vehicle) go down the road a little better.”

Vehicles made since about 2008 have tire pressure monitor systems. But tire pressure can be from 5 to 7 pounds below the recommended pressure before there’s a warning light, Rogers says.

“As people depend more on the lights on the dash to tell them there’s something wrong with the car, the interval period from when you’re starting to have some loss of fuel economy, loss of performance, wear on the tires, is pretty broad,” Rogers says.

Remember the filters: Check and replace air filters that are dirty, or at the manufacturers’ recommended service intervals, Rogers says.

Some manufacturers suggest changing air filters at 10,000, 20,000 or 30,000 miles. However, if you drive frequently on dusty roads or rocky roads, or during harvest time, filters could be clogged before service intervals arrive.

Dirty filters “will cause the engine to overwork and labor a little bit, and every time the engine labors, it’s just trying to draw more air in past that dirty filter. It’s going to take more fuel and use more fuel,” Rogers says.

Reduce the vehicle’s weight

If you’re carrying stuff you don’t need in the trunk, you’re making your car use more gas.

“By putting more weight in your car, you’re decreasing the fuel mileage. If you add 100 pounds of weight to your car, it’s just like carrying another person around with you,” Kimbro says.

HYPERMILING

The popularity of hypermiling — driving a vehicle in a way that maximizes gas mileage — has increased both with rising gas prices and as people pay more attention to environmental issues, according to The Ultimate Guide to Hypermiling: 100 Driving and Car Tips and Resources.

Some hypermiling tips from Rogers and Kimbro:

Ease off the gas pedal

Coast to stops when possible, Rogers says.

“The compression in the engine will cause the vehicle to slow down a little bit, so you can actually use that engine braking component to aid in getting the vehicle to a stop,” Rogers says.

Slowing down may mean it takes longer to get through town, but it’ll take less gas.

“If the speed limit in town is 30 miles per hour, then run 30 miles per hour, not 40 miles per hour,” Rogers says. “If you’re city driving, you can slow down a little bit earlier, so you’re coasting now, and you don’t have the throttle valve open that’s going to demand more fuel.”

Watch your revolutions per minute (RPM), or engine speed

Drivers can check engine speeds with tachometers. Pick a number — say, 2,000 RPM or 2,500 RPM — and practice not going over that RPM.

“Keep your RPMs down when you’re driving, so when you take off from a stoplight or sign, there’s no race you’re in. If you gradually accelerate, you’re going to save some money,” Kimbro says.

Use cruise control on the highway

“We’re supposed to engage those cruise controls periodically so all the cables and the mechanisms in them do not freeze or stick up for when you do want to use the cruise,” Rogers says.

Turn off air conditioning

“When you turn on your air conditioning, you’re putting more of a load on your engine,” Kimbro says. “If you have a lot of electrical loads in your car, meaning if you’ve got a lot of accessories in your car, like an amplifier, mini frig, stuff like that, those are all electrical loads on your car. All that will actually drag the power down on your vehicle.”

People can be set in their ways when it comes to gas mileage in their vehicles, Kimbro says.

“They’re going to continue to do the same thing. The only thing they’re going to do is they’re just going to complain a little more when they put gas in their car,” Kimbro says.

Tamara Browning can be reached at 217-788-1534.