Why not? Serious question. Maybe not today, but one of the new 3D printers includes arms to assemble the parts produced. I wouldn't be ready today to trust my safety to extruded plastic doo-dads, but I don't wee why I wouldn't eventually use a car 3D printed out of the proper materials.
I believe this is a reference to the absolutely idiotic advertising that the copyright industry shows exclusively to its paying customers.
It used to be that there would be FBI warnings on disks that went something like "You wouldn't steal X, you wouldn't steal, Y, you wouldn't steal a car, downloading is stealing."
Which of course is an issue if, like me, you totally would copy a car.