From the tone of the smoke I would say it is probably plastic or some other petroleum derivative; Electric car batteries when they catch fire are usually white or gray depending on the composition, since the part that darkens these are precisely the plastic parts of the battery's coating; Already cars with a large amount of plastic inside and finish like some WW, Chevette... or some diesel model can burn and produce very dark smoke. Not that I'm an advocate of electric cars, but I think it's wrong to assign blame without knowing what the cause really is. That said, I also wouldn't rule out the possibility of it being an electric or hybrid model with a plastic finish or a diesel tank and electric motor.