From its launch in late 1994, the Audi S6 was powered by a 2,226 cubic centimetres (135.8 cu in) turbocharged inline five-cylinder petrol engine (parts code prefix: 034, identification code: AAN) with a Bosch Motronic electronic engine control unit (ECU), producing a motive power output of 169 kW (230 PS; 227 bhp) at 5,900 rpm, and 326 N⋅m (240 lbf⋅ft) at around 1,950 rpm, whilst consuming high octane "Super Plus" 98RON unleaded petrol.

The vehicle was available with a standard six-speed manual transmission (five-speed only in North America) and with the four-plus-one-speed automatic (the fifth "gear" called a 'lockup' gear, what reduced the RPM by ~400 at highway speed with cruise control on) as well, with the Audi's dynamic Torsen T-1 quattro permanent four-wheel drive system.

Audi made a high-performance, 4.2-litre V8 engine (parts code prefix: 077, identification code: AEC) with a Bosch Motronic ECU available as an option in the original European S4s, and made the decision to continue to do so with the S6, making a 213 kW (290 PS; 286 bhp) version of the 4.2 available as an optional upgrade over the 2.2-litre inline five-cylinder turbo.

Unlike the five-cylinder turbocharged version, the V8-powered S6 was supplied with a four-plus-one-speed automatic transmission as standard, but kept the quattro four wheel drive.

As a swan song to the C4 platform, an even more powerful, and very limited-production Audi S6 Plus (Typ Q1) was briefly available to European customers.

The S6 Plus, developed by Audi's wholly owned high performance subsidiary, quattro GmbH was available for sale during the 1997 model year only (production from June 1996 to October 1997).

Audi's performance division reworked key parts of the internal combustion engine, increasing the motive power to 240 kW (326 PS; 322 bhp).

It had double overhead camshafts on each cylinder bank and solenoid-operated magnesium two-stage variable intake manifold.

The automatic included steering wheel mounted paddle shifters, and a "Dynamic Shift Program" (DSP) for improved gear selection based on driving conditions.

(paddle shift optional) Torsen T-1 based dynamic quattro permanent four-wheel drive was also standard.

The body panels were largely based on the Audi A6 4.2 model, with slightly flared wheel arches and door sills, with the bonnet (hood) and front wings being constructed from aluminium.

Wheels and tyres were upgraded to 255/40 ZR18 99Y XL, or 255/35 ZR19 96Y XL (5/15 arm design), and there was the "Dynamic Ride Control" (DRC) system available for the suspension, which featured diagonally interlinked shock absorbers to give better body control during extreme cornering, acceleration and braking.

This engine is often referred to as a derivative of Lamborghini's 5.0-litre V10, but with longer stroke and wider bore to provide additional low end torque for use in the heavier sedan.

The engine is managed by a Bosch Motronic MED 9.1 electronic engine control unit (ECU), which controls the mapped direct ignition, ten individual spark coils, common rail cylinder-direct sequential multi-point fuel injection, and drive-by-wire throttle.

The same engine is used in the Audi D3 S8, but in a higher state of tune where it develops 331 kW (450 PS; 444 bhp), as the S6 is not to be positioned above the S8 in output.

However a test by Edmunds found that the S6 takes 5.7-seconds to reach 60 mph (97 km/h), a full second or so behind the BMW M5 and Mercedes-Benz E63 AMG (which are the S6's closest competitors in North America, since the RS6 is not sold there), and that the 2009 Audi A6 3.0 TFSI (a supercharged 3.0L V6) has almost equivalent performance to the S6 5.2 FSI.

The S6 features two rows of five distinctive LED daytime running lamps (DRLs) along each side of the front bumper air intakes which indicates the 10-cylinder engine as a point of differentiation from other A6 models.

[4] Bi-Xenon high-intensity discharge (HID) adaptive headlights which swivel around corners complement the LED DRLs.

This version of the RS6 included a 5.0-litre (4,991 cubic centimetres (304.6 cu in)) even firing 90° V10 twin-turbocharged ("biturbo"), Fuel Stratified Injection (FSI) V10 engine, which produced 580 PS (427 kW; 572 bhp) and 650 N⋅m (479 lb⋅ft).

The Audi S6 and S7 are powered by a 4.0L DOHC twin-turbo V8 engine mated to a 7-speed S-tronic Double Clutch Gearbox.

Changes include: The Audi S6 C8 is powered by a 2.9 litre twin-turbo V6 TFSI gasoline engine, producing 331 kW (450 PS; 444 bhp) and 600 N⋅m (443 lbf⋅ft) of torque, allowing the car to reach 60 mph in just 4.4 seconds.

European models went on sale in summer 2019 and feature a 3.0 litre turbo-diesel V6 producing 253 kW (344 PS; 339 bhp) and 700 N⋅m (516 lbf⋅ft) of torque, accelerating the car to 60 mph in 5.1 seconds.

[13][14][15] Both engines feature an electric supercharger or compressor, originally debuted on a diesel powered V8 in 2016 Audi SQ7 TDI.