Audi endows the RS6 Avant Performance with a twin-turbocharged 4.0-liter V-8, which generates 621 horsepower and 627 pound-feet of torque. The powerplant combines with a 48-volt hybrid system that's found on other Audi products, such as the A8 luxury sedan and the Q8 crossover. The RS6 Avant Performance feeds its standard Quattro all-wheel drive through an eight-speed automatic transmission. The RS6 Avant Performance lightweight wheels and a revised center differential. But those numbers don't accurately demonstrate the wagon's glorious ability to increase our heart rates and tingle our eardrums with its breakneck acceleration and badass soundtrack. Rolling on a set of 22-inch wheels with summer performance rubber and buoyed by a sport-tuned air suspension with adaptive dampers, our RS6 Avant test car was able to deliver a relaxed or rollicking ride depending on the selected drive mode. The long-roof Audi also felt extremely agile thanks to its four-wheel steering and torque-vectoring rear differential. Ours stopped from 70 mph in a tidy 160 feet with the standard brakes. A set of front and rear carbon-ceramic stoppers are available for a sizable sum, and the upgrade unlocks a higher top speed of 190 mph