Originally Posted by
Fizzer
Until reading these threads I was under the impression that if I "guessed" I needed $50 but only needed $30 the gas station would get to keep the $20.
Actually you don't even have to say an amount. Just say "full fillup" and leave your credit card with them as collateral. They'll open the gas pump for you and once done, you go back inside and they'll just ring up the amount you pumped in.