How does it pass safety regulations without an integral part of the vehicle? How do they publish performance data if it can't move on itself?
Not that those are insurmountable obstacles, but a law that says "You can't claim your vehicle does 200 miles on a charge if it doesn't include a battery" or "You can't claim your vehicle is safe in a frontal crash because the battery absorbs some of the energy except you're not including the battery" don't seem unreasonable.
There is no specific regulation, other than selling incomplete products as completed products.
For example, its perfectly legal to advertise a car as saying its a car without engine. You just cannot advertise it in such a way that the viewer thinks he can buy the car and just enjoy it.
How's this any different than the situation with PC parts? You have CPU and GPU manufacturers advertising their products with images of games being played, yet you need to buy half a dozen other parts before you can start gaming.
Not that those are insurmountable obstacles, but a law that says "You can't claim your vehicle does 200 miles on a charge if it doesn't include a battery" or "You can't claim your vehicle is safe in a frontal crash because the battery absorbs some of the energy except you're not including the battery" don't seem unreasonable.