All discussions in regard to Super Touring must always, always, always divorce engine and chassis discussions. Because we can so freely swap family engines in family chassis, they may be coincidental but they are not directly related.
So for example, "the RWD Miata is not dominant because it has a lower-powered engine" or "the Honda Civic is a great car because it has a powerful engine" is an invalid discussion point. On the other hand, "the Honda Civic is a great strut chassis" and "the Miata is a great sports car option" are valid discussion points.
Engines should be adjusted by engine-related inputs/factors; chassis should be adjusted by chassis-related inputs/factors. There are crossovers, such as power-to-weight considerations and/or effects of weight on chassis, but they are otherwise parallel lines that should not meet.
Because we have some flexibility with aero in Super Touring, I'm not that stuck on aero considerations. We add air dams, undertrays, splitters, and wings, and we lower the car to reduce the amount of underbody airflow. All go a long way toward improving - and in some case, hurting - aero, but in a generally-equitable way*.
There are other non-quantifiable; the Miata, for example, gets its factory cD numbers off the base car, which is a convertible. Yet, we allow the factory hard top, which no doubt goes a helluva long way toward improving that cD. And, related to above, the STL-compliant airdam goes a long way toward cleaning up the jelly bean nose that forces a lot of air under the car.
The one manufacturer-published aero factor that seems significant to me is frontal area. I see that as a general characteristic of the size of the hole that the car has to punch through the air.
GA
* "Hurting" meaning rear wings. Which, of course, benefit RWD cars a shat-ton better than they do FWD cars... Airdams increase drag as well but their benefits far outweigh that, and generally equitably among most cars, regardless of drive layout.
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