Considering a gasoline rewards card? Read the fine print - and don't carry a balance

With fuel prices taking a bigger bite out of budgets, you may be considering an offer for a gasoline rewards card.

These cards typically let cardholders accumulate points in exchange for a gift card or receive cash back on purchases. The savings typically run from 3 to 5 percent of your gas bill.

As with any credit card, you'll find considerable differences, so be sure to read the fine print. Take time to go beyond the savings rate and check out savings limits, interest rates, and other features.

What's more, investigate whether a general rewards card offers any discounts for fuel purchases.

If you don't like toting around multiple cards, sticking with a general rewards card may be your best bet. But the savings on fuel with a general rewards card may not be as high.

"The advantage of gas-based cards is that you lock in a savings rate," said Doug Miller, senior analyst at Corporate Insight, a market research firm. If you rely on a general rewards card, the issuer can change the terms for fuel savings, or place other limitations on when you can save.

Bankrate.com offers a comparison tool for gas rewards and other types of credit cards.

If you're on the road a lot, a gas card is worth considering. One benefit is that the rebates are usually automatically credited to your account, or a gift card is sent, Miller said. It's not like a frequent flyer program where you might accumulate countless points, only to forget to redeem them before they expire.

There are potential traps, however. For starters, make sure you're not being enticed by an introductory offer under which the terms will change after a set period. Some issuers may give double the rate of savings for the first several months.

Also keep in mind that gas reward cards typically don't offer as high a rebate on nongas purchases, often around 1 percent.

Another option is universal gas cards, which let consumers reap rewards at any station. The major drawback is that they often cap rewards.

For example, Discover's universal gas card, the Open Road card, offers 5 percent cash back - but only for the first $100 you spend each month. In other words, you'd save $5 at most every month.

Open Road offers other perks, however, such as a 5 to 20 percent cash-back bonus at certain online retailers and 1 percent savings on other purchases after total annual purchases exceed $3,000. Assuming you stop at the same gas station most of the time, a card that's tied to a particular gas retailer is probably a better deal. These cards generally don't limit rewards and offer 3 to 5 percent savings.

Also check that savings rates aren't "up to" a certain level. That means your savings are at a lower rate until you spend a certain amount of money. "You may have to spend $2,500 before you get 5 percent back" Cannon said.

Lastly, don't carry a balance. Interest payments will eat into savings you earn.

Candace Choi is an Associated Press writer.