It bothers me when we leap to "because Miata," particularly since that's not my argument here - it's just a case that illustrates my concern. There are separate variables involved:

** 2-seat vs. 4-seat (touring car) chassis layout - influencing frontal area, height (so windshield angle; thanks Lizard!), CG height, MMI, etc.

** Strut vs. DWB suspension architecture

** FWD vs. RWD

I personally don't think that we can accommodate everything that's included in the first with an adder, and (as admitted) have a theoretical/conceptual issue with a "touring car" class including sports cars. It might be, though, that an additional penalty for sports/GT cars would be appropriate, on top of penalties for suspension design and drive layout.

The net for the Miata stacks up but that's probably appropriate as its inherent advantages do, too.

K