Some folks take two vehicles. The limit is 35 gallons for the points savings. I know a guy who does that once or twice a month. He has to commute once a week to Louisville (probably 200-250 rt). He is a airline mechanic working at a Fedex hub, or is it UPS???
My wife's car has an even smaller tank, so I try to fill mine. Just this evening I emptied a 5 gallon into a 2 gallon can(Twice), and a one gallon.
These new cars have a special size slot for the gas to go in. They provide a plastic spout and you have to insert that, then pour your cans into that. Its kind of a pain, but its nice to save a few bucks, and not have to go to the gas station for a few more days.
Greg