There should have been a provision in the legislation allowing the construction of e-x-a-c-t replicas - engines and all. It's a darned shame there wasn't.
Given the number of miles driven, the average city transit bus pukes more crud into the air in a month than an entire year's production of "exact replicas" would in their lifetime.
Think about the logic(?!) for a second. A company like, say, Superformance, can build an entire completed car minus its engine and transaxle...ship it to a customer who then installs ANY engine and tranny he wants - and that's fine. But, Superformance itself can NOT install the very same engine & tranny for that customer and ship it to him! What's the 'bottom line' difference once the ignition key is turned???
'Too darned 'deep' for me...