It's all very complicated, even with a background in (criminal) law I can't really fathom it -
To me it looks like literary and artistic copyright lasts for 70 years after the death of the creator, but that doesn't really cover car designs.
That's more likely to come under 'Design Right' so expires a maximum of 15 years after the design was created, meaning most of the cars we're replicating are comfortably outside that time limit.
I think that the issue the big players have, like Bentley, Mercedes and Fennari, is infringement of their trademark, especially when applied to an inferior product.
Just to buck the trend, I understand from the Chesil website that Porsche actually steer potential customers who enquire about used 356's to their door, so they at least are happy to see thousands of beetle-based Speedsters representing their brand. Not too sure how they'd be about the badges, though.
Mine's going to wear Wendler Reutlingen
Coach Builder badges as they're no longer trading, but I also have a couple of gold plated 'P_____e' scripts that might make an appearance...