Well I think it's still working with some explanations:
the only two examples that are wrong I think are pagani and lambo... but put it this way:
those are super cars, so obviously sporty, and I don't think we can call the diablo and the c12 'coupe' so their 'topless' version can't be seen as derivative of 'coupe' . if the top disapear, they moved from supercar to roadster... or perhaps superoadster...
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