Audi even outlines pricing for the high-performance models in the US: The RS6 Avant Performance and RS7 Performance use a twin-turbo 4.0-liter ... sound is an optional upgrade.

Even though the RS6’s big, 4-litre twin-turbo V8-powered estate was always ... more eagerly when you touch the throttle. Abt’s upgrades probably don’t make much sense if you don’t have ...