i prefer just to put my $4/gallon 93 octane good ol fashion rag head oil produced fossil fuel into my mazda.
Propane, hydrogen, etc. are all good new alternative means to powering our vehicals, but bigger jumps in technology are needed before they can become viable. I believe instead of putting the exspensive technology of splitting hydrogen atoms across a membrne to separate a single electron etc. they do make the hydrogen eletric cars.... they should put that technology into the power plants and use the "green energy" produced from the power plants to power our eletric cars.... thats only if i get a tesla roadsters w/ a working 2 speed transmission.