I found a joke in a 2003 auto magazine that I sent him.

A guy pulls into a gas station with his H2 and starts filling up. An hour goes by, then two then three. Finally the gas station attendant comes out and suggests that he shut the engine off.

My friend did say he was now driving 65-70 on the interstate and he's gotten his interstate milage up from 10.5 to 13! I told him my GREEN friends would be proud of him