With gas approaching $4 per gallon, it's natural to think about ways to drive less. But for many of us, there are only so many car trips we can cut, and our fuel budgets can only stretch so far. Fortunately, there are several ways to shave pennies off the price of gas if you're a careful consumer.

Take David Christensen, who commutes from his home in Inver Grove Heights to Stillwater, where his employer relocated in 2006. He tried ride-sharing and bus riding, but neither were compatible with his work schedule. With a $300 monthly gas tab at today's prices, "I have to save money on gas somehow," Christensen said. So he started using www.Twin CitiesGasPrices.com to spot low gas prices and shares his observations on the site under the name "BargainHawk."

That website, and others like it around the country, rely on dedicated users like Christensen to note gas prices at stations around their homes and workplaces and send them into the site.

In addition to tracking which stations tend to have higher prices, Christensen uses gas coupons that he finds in both the Pioneer Press and Star Tribune. But he doesn't necessarily use the coupons from Holiday Stations and Kwik Trip at those stations. "Many stations accept coupons for their competitors," Christensen explained. He estimates savings of about $61 a year with coupons, which he acknowledges isn't a ton. "But I hate paying full price for anything," he said. Some stations post coupons on their websites, so it's worth a look before heading out. Coupons can also be found on the back of register receipts, most commonly at grocery stores.

Stephani Simon saves money on gas by buying groceries. She joined Rainbow Foods' Roundy's Rewards Fuelperks program, which for every $50 spent on groceries saves members 5 cents per gallon on up to 20 gallons at participating BP gas stations. Simon isn't a penny pincher and was resistant to the idea of another program to keep track of. But the 35-year-old from Brooklyn Park says this program doesn't take a lot of time or brainpower. "We need to buy groceries anyway and we're already buying there," she said. Her family of three spends about $400 a month on groceries, which equates to an $8 maximum discount at the BP station near her house.

Members can learn more as well as earn more rewards by shopping at participating online retailers at www.fuelperks.com. The Fuelperks program is currently scheduled to end on July 9, but has been extended before. A Roundy's spokeswoman couldn't say if the program will be extended again.

Prefer plastic? Then consider a credit card that has higher cash back rewards for buying gas, but only if you don't carry a balance. Rewards cards usually have higher interest rates, which will cost a consumer far more than can be made up with the 1 or 2 percent discount on gas, said Ken Lin from CreditKarma.com. Lin said American Express has some of the best rewards for gas purchases. He mentioned the Costco TrueEarnings Card, which earns 3 percent cash back on up to $3,000 in gas purchases per year. Many rewards cards have smaller spending caps, so be sure to check. The annual fee is waived with a Costco membership, which costs $50. Costco also has the reputation of having gas that's routinely cheaper than the average gas station.

Lin said the best card out there for gas rewards is the BP Visa card issued by Chase. It offers a 5 percent rebate at BP stations plus double rebates for the first 60 days.

If you steer clear of credit cards, some gas stations offer point-based rewards programs of their own. SuperAmerica has Speedy Rewards, which you earn by buying gas and merchandise at its convenience stores. The rewards can be redeemed for anything from free coffee to a 50-cents-per-gallon discount on gas.

SuperAmerica also offers Pay Card, a fee-free, PIN-based debit program that links a Speedy Rewards loyalty card to a consumer's existing checking account. This enables the gas station to bypass the fee it is charged by banks when a customer uses a traditional debit card. Because it's cheaper for SuperAmerica, the station offers double points on all Pay Card gas purchases.

Not up for new credit cards or carrying coupons? There are several iPhone apps that track gas prices and monitor your car's fuel economy. Try free apps such as GasBuddy or Cheap Gas!, or track your car's fuel efficiency with GasHog or Accufuel, which both cost 99 cents.

Finally, there are the simple tricks to conserve gas while behind the wheel. I'll share a list of common tips on my blog: www.startribune.com/mcguire, where I hope you'll share your gas savings tips as well.

Kara McGuire • 612-673-7293 or kmcguire@startribune.com. Twitter: @kablog.