TheSmokingTire reviews the rare Audi RS6 Avant GT, a limited edition with 621 horsepower, inspired by Audi's Trans Am racing car from 1989. Differences from the RS6 performance include carbon fiber hood, new front splitter, and 10-piston carbon ceramic brakes. The GT lacks a roof rack and sunroof, features a unique rear differential for a more rear-biased feel, and comes with triple adjustable coilovers instead of adaptive air ride. The car's suspension and brakes are lighter, enhancing control and response. With a top speed of 190 mph and 0 to 60 in 3.2 seconds, the GT offers impressive performance and handling on the track. Despite a $100,000 higher price tag than the RS6 performance, the GT appeals to Audi enthusiasts who appreciate its racing heritage and fast wagon capabilities.