The Tesla Model S is a great-looking car but, unlike some, I still don't see electric cars as being the future. Batteries are still too heavy, take too long to charge, are too expensive and require materials that in widespread use will probably become far more of a problem than fossil fuels in terms of scarcity. Of course, there can be and no doubt will be technological innovation in this space but (IMHO) the future…
Unlikely to be ammonia. Ammonia is dangerous in the kind of concentrations that would make it useful for fuel. When ammonia was used in refrigeration whole families would occasionally die when their refrigerator sprang a leak.