Some of the newer hybrid drivetrains, like the new Honda Accord Hybrids, are basically electric cars mated to a gas powered generator and instead of a big battery just have a gas tank - a smaller battery bank "caches" the generated energy. Thus you only take it to the gas station every ~600 miles and don't bother the rest of the time.

(and yes, the gas engine in this kind of drivetrain will mate to the electric motors during power intensive operations for a boost, but that's not strictly required in this kind of approach)