What I have done is the following:-
If there are two of you one goes inside with credit card and stands there whilst the other fills it and then you pay. Same with cash.
Paid a certain amount on card e.g. $40. If the tank only needed $30 then go back inside and get refund on card. Same with cash.
Gone in and said card doesn't work in pump. They hear my English accident and tell me to go and fill it up and then come back to pay.
Petrol (hire cars have always been petrol) is so cheap that don't preauthorise a high amount as PP have said. Also petrol pumps tend to be black which takes a bit of getting used to given that's the colour of diesel pumps in the uk.