Just a 'proof of concept' at this time. About 10 gallons in 1999 for 7 trips up
to 120 miles. Not very efficient at about 15 miles per gallon. Only adds about 15
miles per hour of run time. About 30 hp engine, 15kw electric output (20kw gen)
needed for continuous highway operation. A small car engine will be more suitable,
preferably run on propane for longer life and lower emissions.