This is what we do - but with a little extra twist
Our grocery store - Smith's - normally gives 2x the fuel points if you buy a gift card. They often have promos where you get 4x points for buying a gift card. So, as a result, we buy a ton of gift cards. We use Amazon Prime subscriptions for a lot of our basics - TP, deodorants, diapers, shampoo, soap, etc. When we go grocery shopping, we just pick up a few Amazon cards to pay for the subscription stuff. If we're working on a project that requires a trip to Home Depot, we pick up a gift card for HD on the way. (We live close enough that the Smith's is on the way to pretty much everything for us.) Even do the gift card thing for going out to dinner - just pick up a restaurant card if we're planning on going out later in the week.
As a result of this, we stack the fuel points up big time. Yesterday I filled up with an 80¢/gallon discount. Usually, we have the max discount of $1.00/gal saved up. The nice thing about Smith's is that they're all over Utah, so we can fill up with these discounts just about anywhere in the state. The discount also carries to other Kroger stores, but with varying success. When we travel to California, we can use our discount at Shell stations, but the discount caps at 40¢ (I think). The discount also only applies to 35 gallons per fillup, so we usually fill both of our cars at the same time, or bring our gas cans along to top off. Of course, if I'm filling the Bronco, I usually consume most of the gas myself. Bronco is a thirsty one, w/ a 32 gallon tank.
If it sounds like a pain, it can be, but the savings are worth it to us.