The eTron prototype had screens in the door just below the windows, so they were in the same general area as mirrors. Japan has legalized them, but I haven't heard of any other jurisdiction legalizing them yet.
New videos show how Audi E-Tron’s new virtual side mirrors work
The slowness of regulators to legalize cameras to replace mirrors is one of the driving reasons that I think even when self driving tech has been proven it's going to take years before many jurisdictions legalizing it. Rear view cameras are minor tech compared to self driving tech. The problems with rear view cameras are drastically fewer and simpler, yet regulators are hesitating to go for it.
This article from 2014 says mirrors create 2% to 7% drag.
Why It'll Be a While Before We Can Replace Car Mirrors With Cameras