azotic writes:

http://www.motherearthnews.com/libra..._Run_My_Car_on
_Acetylene

Hydrocarbons are a near ideal fuel. The energy density and "hazard
density" are extremely low. Calcium carbide, like ethanol, carries a lot
of dead weight. Hydrocarbon fuel-air mixes are explosive, but not anything
like acetylene. Heard those tales of garbage bags inflated from a welding
torch?

Consider boron metal instead of carbide. Zero emissions: you capture the
exhaust and regenerate it at home with electricity. The fuel is dense and
not too hazardous to store, so unlike gasoline, you could stockpile large
quantities at home to improve distribution efficiency. The big problem is
a practical engine.