Regarding "legal", knock-offs are not legal on new cars in the US after 1968. However, nobody from a legal/DOT perspective is likely to know exactly what a M3W is, and in any event, the M3W would not be legal as a new car in total, so it's a mute point as to their status on a car... I question if a M3W could be sold new with them "factory" installed, but I don't know for sure.
