For all those people representing metro's. Found a Turbine engine mounted to a metro torque converter and auto transmission. 100 hp. and only weighs 68lbs. From what I've read turbine engines are 60% efficient, as apposed to ICE's 30%. It's a lot of money to double your FE but it would be awesome.
eBay Motors: TURBINE ENGINE JET ENGINE TIERNAY TT10-1 FREE SHIPPING (item 170268610227 end time Oct-09-08 13:28:02 PDT)