You can get a regular credit card from a major bank that offers cash back rewards on all purchases, including gas purchases. For example, it can be the Discover it® Chrome card. This card doesn’t require sign-ups and has no rotating rewards categories. You will simply earn cash back on all purchases. There is no annual fee and you will be able to take advantage of 0% intro APR on purchases. You can keep this card as your primary card, or use it for gas purchases only.