A Touring car has 4 real seats. The 2 seat 4 seat performance difference is mostly the sum of windshield angle and vertical CG ratio to track.
The CRX/Civic perform about 100# apart as do the VW Scirocco/Rabbit. Both cars are about 6in lower than the sedan version and turn better as a result.
For the ST cars there are no direct comparison RWD cars. (Lotus 7 and Lotus Cortina? ) Maybe the Miata and Ford escort GT?
The Miata are very well driven,and can out perform their expectations due to the best drivers trail braking to the apex. Not many FWD cars can do that.
The miata can sustain very high lateral grip values that taller cars cant due to overheated outer (front) tires. The notes about WGI with breaking parts and high G loads is common in the T5, T6 and toe turns- the banking adds a lot of loading that the Miata loves. 1.5-1.6 is common there. The feel of the Miata is very solid, while the sedan is more like HS I'm gunna punch that outer tire wall evry lap.
I dont see why the class exist either.