Trains:
They have diesel engines, but they only power generators that create electricity to drive electric motors that actually power the drive wheels. So, why doesn't someone do a hybrid diesel / electric where a 50ish hp diesel powers a generator which powers electric motors at the wheels? Stupid amounts of torque, more power than you'd ever need. Pair that with a crap-ton of batteries and the engine could shut itself down from time to time.
P.S. BMW owns the pattents to solenoid driven valves, iirc.