Saving a few bucks at the gas pump is always nice, but signing on for a gas station-branded credit card might not be the way go about it, according to a new report.

CreditCards.com’s latest survey  finds that using a major gas brand’s credit card to fill up every week might reduce the price of your commute, but the high fees associated with such cards and meager rewards could cost more in the long run.

A survey of the 20 largest major gasoline-brand cards found that fuel savings earned per trip to the pump varies greatly. On average, customers save just $0.10 per gallon, which translates to a 4% savings (or $6) if you spend $150 on fuel each month.

While a 4% savings might be better than average general purpose credit cards that offer between 1% and 3% in rewards, CreditCards.com found that — for consumers who don’t pay off their balance in full every month — the benefit of the lower gas prices may be wiped out by high annual percentage rates

On average the APR for a gas card is 24.14%, while traditional general purpose cards average an APR of around 15%.

In addition to questioning the high APRs associated with gas-branded cards, the report found that the overall reason to have the cards – fuel discounts – might not be worth it, unless gas prices remain low.

“The per-gallon discounts commonly offered by gas card reward programs give the most back when gas prices are low, since a 10-cent discount off a $2 gallon is worth more than 10 cents off a gallon costing $5,” the report says.

Another downside to the cards occurs when trying to obtain rewards, thanks in part to a wide range of minimum spending thresholds and restrictions on qualified purchases, the report says.

Six of the cards from the CreditCards.com survey require that cardholders to buy at least 45 gallons of gas each month before rewards start kicking in, which could be hard to reach if commutes are short or you only drive on the weekends.

On the flip side, consumers who do a lot of driving might not be rewarded for their spending at the pump, as six of the cards set a maximum limit on fuel rewards. For example, the Conoco Personal Card and the 76 Personal Cards only allow a maximum of just $99 in statement credits a year.

For consumers looking for a better deal, the reports points out that many gas stations are partnering with local grocery stores to offer rewards programs. In many cases those programs offer a cents-off-per-gallon reward based on the items you purchase at the store.

“They don’t give cents off based on what the customer spends, they give the cents of based on what the customer is buying and that’s a huge difference,” loyalty program expert Brian Woolf tells CreditCards.com “Customers who want cheaper gas can just buy items that are part of the fuel savings program. It’s that simple.”

Gas card survey finds pedestrian rewards [CreditCards.com]

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