I guess what confuses me most is what people mean when they say 'clone'. I'd call a car a 'clone' if it was originally another model, right? I mean, you buy a 70 Challenger R/T with a 340 engine, replace the engine with a 440 and change the suspension and drive train with it, that's not a clone to me. That's just making it into the car you want. It's still a Challenger R/T - you've put in all the stuff you need to make it handle that bigger engine and drive the way you want to, surely that's just 'perfecting' the car to your requirements?
I'd only call a car a 'clone' if it was changed significantly. Changing from a 'Barracuda' - installing new engine, suspension, drive train, etc to make it into a 'Cuda' and changing all the decals on the car to 'Cuda' - that would be a clone to me - because you've made it into something it wasn't before. Yes, it's pretty much the same as I said with the Challenger - but the Challenger started off as the model it still is, you've just 'upgraded' it.