that will charge you less if you pay cash rather than a credit card (but I don't know if the discount applies if you use a debit card). But I've never heard of a gas station doing the same.
I need to look into signing up for the loyalty program at Shell. I used to just put the cheapest gas I could find into the tank but Dad watched some YouTube videos that said you should look for something called "top tier" gas (you can Google which stations sell it). Top tier gas has more detergent additives than required and supposedly keeps engines cleaner and fuel lines less gunked up, supposedly either delaying or saving you from costly repairs down the road. Shell charges its loyalty program customers 10 cents a gallon less.
I also know a ton of people who have Costco memberships and are always filling up there since their gas is usually about 25 cents/gallon less than other stations. Costco gas is top tier gas but the lines at the pumps are always 5-6 cars deep at my local Costco so even if I was a Costco member, I'm not sure I'd have the patience to get gas there.