I would wait a while until the first generation anti-hydrogen fueled vehicles go into production. A few grams of anti-hydrogen (its a very lightweight fuel) would see the vehicle never require a fuel refill and would solve the problems of fuel distribution when moving over from hydrocarbon based fuel. Vehicle accidents might be a problem though.

It is even more environmentally friendly than anhydrous ammonia, as unlike all chemical fuels produces absolutely no chemical byproducts to harm the environment.