How to save real money on gas

This post comes from Kelli B. Grant at partner site SmartMoney.

Gas prices are inching toward record highs, but experts say how you drive and where you buy your groceries can cut the cost of filling up.

Prices at the pump currently average $3.84 for a gallon of regular unleaded, 30 cents more than a month ago, according to AAA. (The record is $4.11, hit in July 2008). Drivers in 16 states and the District of Columbia pay even more -- and in eight of those states, prices already top $4 per gallon. Consumers shouldn't expect relief in coming months, either, says Tom Kloza, chief oil analyst for the Oil Price Information Service. The cost of refueling typically peaks in May after refineries complete the switch to summer gasoline blends, which are more volatile adn more expensive than winter blends . As a result, drivers could see prices rise an additional 5 to 25 cents, he says.(Post continues below.)

Some motorists are better positioned than others to save, experts say. People in states along the Rocky Mountains have some of the lowest prices nationwide -- as cheap as $3.43 in Wyoming -- thanks to their proximity to U.S. supply and refineries, Kloza says. And drivers cruising around in 2012 models may experience the fruits of manufacturers' latest fuel-efficiency push, says Jim Kliesch, research director for the Union of Concerned Scientists' clean vehicles program. Many new models offer features such as lightweight metals and stop-go technology that shuts off an engine at stoplights and in gridlock, he says.

But most drivers need to make more of an effort to save on gas by taking smaller actions that improve fuel economy and reduce costs. "No one individual (fuel-efficiency) tactic stands far above the rest," says Kliesch. "It's a handful of simple things you can do that together offer a reasonable improvement in your fuel economy."

Driving a vehicle that isn't at its most fuel efficient can be equivalent paying an extra $2 or more per gallon, simply because it burns through a tank much faster. Here's how to avoid that premium by filling up less often:

De-clutter

• Savings: Up to 7 cents per gallon.

There's good reason to clean out the junk piled in the trunk, says Kliesch. Every 100 pounds of added weight in a car reduces its fuel economy by up to 2%. That works out to an extra four to seven cents per gallon. Hauling a cargo carrier, bikes, kayaks or other gear atop the car is worse, decreasing fuel economy by as much as 5%.

Weigh payment methods

• Savings: Up to 19 cents per gallon.

As gas prices rise, many credit cards' reward caps on gas purchases kick in, limiting their value, says Odysseas Papadimitriou, chief executive of CardHub.com. He likes the PenFed Platinum Rewards card, which requires a $15 credit union membership but offers five points per dollar spent at the pump. (At $3.84 per gallon, that works out to about $0.19 back.) In some instances it could make more sense to pay cash. Stations may offer discounts of up to 10 cents per gallon for drivers who forgo plastic.

Drive responsibly

• Savings: Up to $1.27 per gallon.

By the U.S. Department of Energy's estimates, every 5 mph faster than 60 mph adds $0.30 per gallon to the gas bill. Aggressive stops and starts waste an additional 33% at highway speeds and about 5% at slower, local speed limits. "Don't try to jump off the starting block," says Avery Ash, manager of regulatory affairs for AAA. Calmer driving translates to savings of $0.19 to $1.27 per gallon.

Check the tires

• Savings: Up to 12 cents per gallon.

Under- or over-inflated tires change the way the car handles, adding drag and speeding wear. That, in turn, reduces fuel efficiency by about 3%. Look on the driver's side door panel or in the owner's manual for information on proper inflation levels, Kliesch says. Don't go by the figure stamped on the tire -- that's the maximum it can handle.

Use grocery discounts

• Savings: Up to $2.20 per gallon.

Many big supermarket chains now tie in-store spending to discounts at the pump. Depending on the program and your typical grocery bill, your savings could range from 10 cents off to as much as $1.50 per gallon at Albertsons or $2.20 at Giant, says Teri Gault, the founder of The Grocery Game. But shoppers may find that prices at partner stations are higher than elsewhere, eating into savings, she cautions. Programs typically cap the amount of fuel you can get at the discounted rate, although households may still be able to fill two cars on the cheap.

Create a fuel-efficient route

• Savings: Up to 30 cents per gallon.

It's possible to cut down on mileage just by running a few errands on the same trip, and choosing more efficient routes, Ash says. On longer trips, use a GPS to find the best route -- and price-mapping apps like AAA TripTik or GasBuddy to find the best fuel deals along those routes. Prices in Ypsilanti, Mich., for example, currently range from $3.81 to $4.09, according to GasBuddy. That's a $0.28 per gallon swing, so it can pay to shop around.

More on SmartMoney and MSN Money:

• Finally, loyalty programs for saving
• Breaking up with retailer email
• Spa deals that pamper your wallet
• Do gas-saving devices work?
• Gas prices are just the beginning
• Calculator: How much vehicle can you afford?