2024 Audi A6 E-Tron, Cd 0.22 fastback
 

https://www.evspecifications.com/en/news/d434437Built on the same Volkswagen AG' Premium Platform Electric ( PPE ) platform as the 2021 Porsche Taycan, the A6 will also share the drag coefficient of the entry-level Taycan.
And the September 2021 MOTORTREND credits the A6's fastback roofline for the Cd 0.22.
The new, Gen-11, 2022, Honda Civic Hatchback also gets a 'proper' fastback roofline, which will be used to create the new Civic Type-R as well.
Glad to see them both.;)

https://www.evspecifications.com/ima...34437/main.jpg
https://www.evspecifications.com/ima...ditional_0.jpg
https://www.motorbiscuit.com/wp-cont...ype-R-side.jpg

Ground clearance, rearview mirrors, very long diffuser and the roofline.
Obviously, the radio antenna is also missing.

I understand the three pair of wheel spats, but what is the purpose of the concavity between the wheelwells (more pronounced raised on the newer body)?

concavity
 

* Near the wheels, on the rocker panels, they may be vestigial wheels fairings, or a visual styling introduction to what may become more formal, aerodynamically, in the next generation.( just get buyers used to the idea of seeing such things on an Audi )[ think Ford PROBE-III ]
* Above the rockers and below the beltline, we may just be looking at a character line, which adds visual interest, plus a structural corrugation to light, thin sheet metal. One of Ferrari's most iconic sports cars, the Testarossa, had enormous strakes ahead of the rear wheels, thought to be some aerodynamic magic, when in actuality were there only to satisfy Italian side crash protection safety standards.
https://www.thedrive.com/news/40700/...n-cars-forever