I'm really surprised at how many people haven't heard of these

I mean of course it's certainly no fix for ripoff prices at the pump, but when you can save 5% or 10% for free, without having to do anything different, I don't get why more people don't take advantage? I've had one of these cards since I think last April or maybe it was May. Anyway I love it because you can use them at any station and then when I'm at the pump and I see the price is $4.00 I just recalculate it in my head "4.00 for me? No it's only 3.60
Then tonight I was Googling reviews for credit cards because my son will need one when he starts college in the fall, and sure enough right on the main page of the site
http://www.creditcardforum.com they had the reviews on which cards were the best for getting the biggest gas discounts.
I'm not saying I'm all about using a card to pay for everything, but I think as long as you pay it off in full every month it won't cost you anything and you'll actually save money with the discounts they give you. Does anyone else here use these?

But what would really help is if I could just afford a Prius