Maybe I can get in with this before the entire debate falls apart... hah, yeah right. Anyway, here goes:
The Copyright equivalent of stealing a candy bar (or a car from a dealership, to use your earlier analogy) from a grocery store is actually:
- Man enters a grocery store and sees a $1 candy bar
- He goes home and produces his own candy bar just like it, with the resources he has available; with his own time, energy, and equipment (stove, mixer, trays and moulds), and ingredients (chocolate, nougat, peanuts, whatever)
- He could eat this bar, give it away, or sell it without having *stolen* anything.
The original candy bar is still available for purchase for $1 to the next customer. If the Man in the example were selling his candy bars for profit, he would have effectively created a competing business to the grocery store. If he sells them wholesale to the store, he's competing with their other distributors.
If they are confusingly similar to the original brand, he may be infringing the manufacturer's protected trade marks. If he uses their patented process to put bubbles in chocolate or something, he may be infringing their patent; but legal competition for manufactured goods is specifically not covered by Copyright law.
Back to the car example, manufactured goods may contain Copyright-protected work, i.e. microcode in the car's engine management unit; but if you build a functional equivalent of your own without infringing patented methods, you're good to go.
Keep in mind that a car manufacturer will have registered 'trade marks' like "the distinctive tail light arrangement" that you won't be allowed to produce competing goods 'confusingly similar to', but you can (YMMV, consult a lawyer) build one for your own use.
And yes, for the sake of argument a physical work *can* be subject to protection by Copyright, but would generally need to show substantial creative effort and merit to be enforced; such as a carved statue. In the case of the car example, the Copyright would apply to the manufacturer's plans, CAD/CAM files, and maybe physical prototypes; but almost certainly not the result of the process (again, YMMV, consult a laywer)