If I could make a perfect copy of a car out of thin air, without depriving anyone of anything, I would "steal it". So would absolutely everyone, and the motor industry would have to change their business model.

What would that business model look like?

Give away the car for free and make money on servicing.

"Low Interest" loans

Hmm.

Designing better cars; making parts for the 3d printers that built the cars.

What do you mean by designing better cars? How would that help?

Also wouldn't there already be an industry that makes 3D printers? Why would the car companies try to go into that business?

Open-source car development, perhaps? Could be neat.

I agree, it would definitely be neat. What would the business model be like though? How would they generate revenue?