Well sure, production of anything takes energy. Question is if 5% of the cars need replaced a year (20 years average age seems about right) are you better off replacing 5% of cars with electric or gas? The studies I've seen show that gas cars are so inefficient (often 15-20%) that even natural gas produced electricity is better in an electric car than a gas car.

The story gets even better if any solar, wind, or hydro is used. Sure nuclear helps as well. Seems obvious to me that we should push on all green energies.