As with the previous generation, the new RS6 is powered by a 4.0-litre twin-turbo TFSI petrol engine, now boosted by a 48V belt alternator/starter mild-hybrid system, which can recover up to 16 bhp (12 kW). The engine also utilises a cylinder-on-demandsystem that can shut off half of its cylinders to boost fuel economy.  

The powertrain produces 600 PS (441 kW; 592 bhp) with 800 N⋅m (590 lbf⋅ft) available between 2100 rpm and 4500 rpm. 

The acceleration to 100 km/h (62 mph) takes 3.6 seconds and 200 km/h (120 mph) in 12 seconds. As standard, top speed is limited to 250 km/h (155 mph), with a further two levels courtesy of optional packs – the Dynamic package allows 280 km/h (174 mph), while the Dynamic package plus grants even more headroom for a maximum of 305 km/h (190 mph). The C8 is the first RS 6 Avant to have the hybrid drivetrain, utilising a Riemen-Starter-Generator and a 48-volt electrical system.[29] The Quattro system has power distribution with 40% for front and 60% for rear. The system can adjust the power distribution up to 70% for front and to 85% for the rear if needed. The adaptive suspension system is 20 mm lower than standard A6 and can lower the vehicle further 10 mm during the high-speed driving or can raise the ride 20 mm at low speed. The Drive Select function gains configurable RS1 and RS2 modes, which are activated by an ‘RS mode’ button positioned on the steering wheel. As well as adjusting the engine and handling responses, they also enable bespoke information on the Virtual Cockpit system.