As the name suggests, these cards repay a portion of your total spending on gas. The proportion is typically 4 or 5 per cent, though some cards offer higher percentages (up to 10 per cent) during the introductory period. The money will normally be credited to your account by the end of the month concerned, though you may have to wait until you have accrued a certain amount - say $20 - before you can redeem it.

Many gas rebate credit cards offer rebates only for certain brands, and some can only be used at specific locations. This is excellent for people who regularly use the same gas station to fill up, but may not be so good if you are the sort of person who likes to shop around for the cheapest fuel, or if your job regularly takes you many miles from home. Likewise, if you are running low on gas, looking for somewhere that will accept your particular credit card can be tedious. Fortunately, however, there is a growing number of cards that can be used at any outlet, with any brand of gas.

Another advantage of gas rebate credit cards is that they will often give you cashback on your other purchases as well, albeit at a lower rate. For example, you might get 5 per cent cashback on your gas purchases, and 1 per cent on any other purchases made with the card.

Gas rebate credit cards are becoming increasingly popular with drivers who want to reduce their motoring costs. This is especially true if you drive a truck or SUV with high fuel consumption, or if your job involves a lot of driving.

Most card issuers pay back the customer in the form of a credit to their account, but some offer gift certificates or other rewards. In some cases you are given a choice. The rewards on offer will have a greater monetary value than the cash rebate, so if you genuinely need the items concerned you may be better off accepting the rewards.

Finally, it's important to shop around before you buy a gas rebate credit card and read the small print carefully. Work out your typical annual spend on gas, and then see which card's terms will offer the most advantageous deal for you. One thing to watch for is that many cards impose an upper limit for the top rate of cashback. The Discover® Platinum Gas Card, for example, pays back 5% on your first $1,200 in gas purchases every year, but after that the rate falls to a less exciting 0.25 to 0.50 per cent.