Really?
Personally, I'd have to see an example of that.
It seems a bit un-natural for an overhead lit, full profile shot scenario. I'd do the opposite ... use a white backdrop so the see-through windows look correct when the background is knocked out ... and possibly use long black or white cloth or set of flats (W or B depends on the color of the car) just in front of the camera (hole cut for the lens), to get rid of the reflections of the landscape behind the camera, and the shooter ... which if included, will look foreign when not in an ambient background that matches. This will also help neutralize WB for color matching the Audi paint. But only on a calm day ... otherwise forget that idea
(there is a reason a lot of this type of work in done in studio).
I'd also take care using a boom strobe moved along the car for stitching ... the inevitable overlap from spill light could cause modulations in tone. I'd just use an overcast sky and do the stitch shots as swiftly as possible to minimize minor exposure difference that can happen even on an overcast day. I'd also shoot a series of single shots of the whole car as back-up to the stitching scenario.
Sorry, it's the Art Director in me ... I did car advertising for almost 20 years and have seen most everything tried.
-Marc
If none of the above is possible, then retouching will probably be needed ... and that in itself is a real art form.