A6 suffered from similar problems with B5/C5 platform A4 and Passat. Premature front MacPherson control arm suspensions are the most infamous issue of this chassis. Electronics components depending on vehicle. allroad/A6 2.7T's engine bay have more space for cooling, so it doesn't suffer from 01 S4's heating issue. As for allroad, most commonly known issue has to be its air suspension. Another known issue is NA-spec allroad is known for underbraking compares to European spec.