Wrong!
If you ever look at the "fine print" of any prepaid Visa/MC/AmEx card, it specifically says "Not for use at self-service gas pumps" (as that typically requires a pre-authorization of extra $$).
Now, I guess one could go inside the c-store/hut and prepay for a set amount of fuel using one of those cards, but given most prepaid cards with a Visa/MC/AmEx logo costs at least 5 bucks, that would be extremely cost-prohibitive.