I don't think mobile fusion reactors are what they're going for. And if you're looking to reduce global carbon emissions try walking, biking or using public transportation. It's true electric cars don't emit carbon the way a fuel based car does, but the production and maintenance of an electric vehicle certainly does.
My reading of "a Tesla powered by fusion power" was that the electricity charging the batteries would come from a fusion generator source. And indeed, a clean electrical source makes electric transportation much more environmentally attractive.
