couple of suggestions on efficiency.

1)when you go to close the gas cap, it needs to click 3 times, otherwise vapor will escape(theres a study somewhere about what % of gas is wasted because people dont tighten the gas cap enough).

2)For some reason, gas pumps in the states do not compensate for volume. This means as gas cools it becomes more dense. basically 1 gallon of gas @ 0 celsius is not the same as 1 gallon @ 50 celsius. because the station tanks are underground, and heatsoak occurs, its generally best to fill up in early morning, right at dawn, when the underground tank reaches its lowest temp.