Multiple turbo failures. Engine shook violently then suddenly stopped in the middle of the road. This same issue happened 3 times affecting both turbos. It may be due to faulty oil filter/strainer. From online research (link below) this is a common problem for C7 Audi s6. https://www.audizine.com/forum/showthread.php/851578-2016-S6-4-0T-Turbo-Failure