To assist their gas engines, Nissan has developed e-4WD, or electric four wheel, which uses electric motors but has no batteries. Is this a hybrid? Yeah. Think of it as a mild series or serial hybrid, which is a kind of hybrid that uses a generator instead of a battery to power the electric motors. Wait a minute, you might say: aren't four wheel drives less efficient than two wheel drive cars? Yes but e-4WD is very light and compact because it's electric.