What is a “strong PHEV”? Put most simply, it is a plug-in hybrid vehicle that can use electricity to solely power the vast majority of the distance it drives on a daily basis. Are there other criteria that might define a strong PHEV? Of course, and I’ll cover some of those below. How many strong PHEVs are on the market? Not as many as there should be, even if we count the used ones, but I’ll cover this more below too.