Membership-based stores like Costco, Sam’s Club and BJ’s Wholesale Club have discounted gas. In some cases, you can use affiliated credit cards to get a double-dip discount: Pay less at the pump and get a cash back bonus. For instance, the Costco-branded TrueEarnings American Express card lets customers earn 3% cash back on up to $3,000 in gas a year.
The caveat: You have to be a member to get the deals. A basic membership at Costco is $55 a year, BJs is $50 and Sam’s Club is $40.