I would keep looking if I were you. Why are we so intent on preserving the internal combustion engine by trying other fuels? Hydrocarbons are the epitome of energy density and another fuel will only be second best. Moreover, we elide the issue of making ammonia. Somebody has to do it and it costs in excess of 100Kcal/mole to make each hydrogen to nitrogen bond. The net effect is that somebody has to use significant amounts of energy to get the job done making the efficiency of ammonia suspect. Also, while there are no carbon emissions, we elide the issue of nitrogen emissions which are also potent greenhouse gases. Battery tech is in its infancy and will most probably out compete any fuel plus combustion engine you can dream up. Churchill once said “You can always count on the Americans to do the right thing…After they’ve tied everything else.” Toyota is a Japanese company but the principle still applies and ammonia is part of everything else, not a solution.