Luggage capacity, measured according to the VDA block method in the Avant ranges from 455 L, to 1590 L with the rear seats folded down. For the saloon, the boot holds 424 L.
C5 powertrain
For the C5 RS 6 powertrain detail, the engine is an all-aluminium alloy 4172 cc twin-turbocharged ('biturbo'), double overhead camshaft, 5 valve per cylinder version of Audi's 4.2-litre 90° V8 petrol engine (parts code prefix: 077, identification code: BCY), developed and manufactured in Germany and the UK by quattro GmbH and Cosworth Technology (now known as MAHLE Powertrain). With the addition of the two turbochargers (one per cylinder bank), the power output of the V8 engine increased to 331 kW at 5,700 to 6,400 rpm, and 560 Nm of torque. The combination of the 4.2-litre V8, variable inlet valve timing, and twin turbochargers give the RS 6 an exceptionally wide power band, with peak torque available from 1,950 to 5,600 rpm.
Further detail includes fully sequential electronic multi-point fuel injection with intake manifold fuel injectors,[4] mapped direct ignition system[5] with solid-state high voltage distribution using eight individual single-spark ignition coils and NGK longlife spark plugs, and three knock sensors. Engine management uses a Bosch Motronic[6] ME 7.1.1 engine control unit, which controls all functions of the engine operation; including fuel delivery, ignition system, valve timing, emissions control systems, and torque reduction control—the latter operating in conjunction with the Bosch ESP 5.7 Electronic Stability Programme, as part of the "Anti Slip Regulation" (ASR) traction control system. The engine is compliant with the European Union Euro3 (EU3) standard, and includes two close-coupled primary catalytic converters (CATs), two underfloor main CATs, and four heated oxygen sensors which manage the cylinder bank selective lambda control. This results in a CO2 emissions rating of 350 g/km for the Avant and saloon in standard configuration.
It has an electronically controlled five-speed ZF 5HP24A tiptronic automatic transmission (parts code prefix: 01L, identification code: GAG) (gear ratios—1st: 3.571, 2nd: 2.200, 3rd: 1.505, 4th: 1.000, 5th: 0.804), with lock-up torque converter in all forward gears. It has "hill-detection" capability, and despite many press articles stating that the gearbox was programmed to "blip" the throttle for downshifting gear changes, no UK owners have ever found this feature to be present. The transmission control unit ECU incorporates "fuzzy logic" with its "Dynamic Shift Programme" (DSP), with the shift pattern adapting to suit individual driving styles. 'Tiptronic' manual control can be achieved with either the floor-mounted gear shift lever or the steering wheel-mounted 'paddles'.
The RS 6 was only available with Audi's Torsen-based Quattro permanent four-wheel drive, utilising the Torsen T-2 dynamic 'automatic torque biasing' (ATB) centre differential (diff), a modified unit which was being used in the 6.0-litre W12-powered Audi D3 A8. The torque from the engine is first routed from the gearbox output shaft to the Torsen centre diff, and then automatically divided and apportioned between the front and rear axles.
The front and rear axle differentials (ratio: 3.197, rear axle identification code: GGW) are a conventional "open" type but utilise an "Electronic Differential Lock" (EDL). EDL is an integrated additional function of the Bosch Electronic Stability Programme (ESP) system, and works by monitoring and comparing the individual wheel speeds across an axle, and braking an individual wheel which is sensed to have lost traction (spinning), thus transferring torque across the axle to the wheel/tyre which does have grip. "Anti-Slip Regulation" (ASR), more commonly known as traction control system[7] completes the Bosch ESP-related driver aids.
C5 suspension and steering
Utilising the same fully independent four-link front suspension, and double wishbone rear, as its related A6 and S6, the RS 6 was lowered by 20 mm, with a 30% stiffer spring rate, and 40% increased compression damping. The RS6 also served as the debut model for Audi's "Dynamic Ride Control" (DRC) system. The DRC system is mainly mechanical, and uses a pump to provide additional pressure to individual dampers (shock absorbers) during cornering, acceleration or braking; to counteract rolling and pitching. The system can adjust the stiffness at each individual damper constantly; to maintain both a comfortable ride on straight roads, and a high level of poise and grip when cornering hard, accelerating, or braking. The DRC's main advantage is that it operates without the need for complicated electronics, as required in similar systems from Mercedes-Benz and other competitors. Its main drawback is that the DRC dampers have been known to fail (leaking fluid from the cross-linked circuits), which can affect the handling and ride quality of the vehicle; some owners have reported needing multiple replacements of faulty DRC units and many drivers have opted to replace the system with simpler and more reliable aftermarket coil-over suspension.
C5 brakes, wheels and tyres
The front brakes feature fixed Brembo 8-piston monoblock brake calipers, working with radially vented and cross-drilled brake discs, sized at 365 mm in diameter, by 34 mm thick. The rear features single-piston floating ATE calipers with integrated cable-operated parking brake mechanism, mated to radially vented disc and cross-drilled, sized 335 mm by 22 mm. Front and rear brake calipers are finished in a high-gloss black paint, with the fronts incorporating the Audi "RS" logo. Both front and rear discs are held in by metal pins to the lightweight disc hub, and allow 1.0 mm of lateral thermal expansion from the hub centre.
Bosch ESP 5.7 Electronic Stability Programme,[8] with Anti-lock Braking System (ABS),[9] Electronic Brakeforce Distribution (EBD), and Brake Assist (BA) was standard fitment.
There were a total of three original equipment manufacturer (OEM) wheel and tyre types available with the RS 6. In Europe and elsewhere, 19-inch wheels were standard, with an optional 18-inch package. In the U.S. market, the 18-inch package was the only available offering.
C5 RS 6 Plus
Between April 2004 and September 2004, there was a final limited run of an even higher-performance RS 6, named the Audi RS 6 Plus. This had an increased engine power output (identification code: BRV), and produced 353 kW at 6,000-6,400 rpm, with the same 580 Nm of torque at 1,950-6,000 rpm. This engine was also developed and manufactured in the UK by Cosworth Technology (now known as MAHLE Powertrain). The additional performance was achieved with a new engine control unit (ECU), and two additional coolant radiators behind the side-mounted intercoolers (these were standard fitment on the standard RS 6 in hotter climate countries). Official performance figures indicate the discipline of sprinting from standstill to 100 km/h in 4.4 seconds. The RS 6 Plus carries on to reach 200 km/h in 20.36 seconds, and has an official top speed of 280 km/h.
The RS 6 Plus came with Dynamic Ride Control (DRC) as standard, and also included a no-cost option of "Sports Suspension Plus", which lowered the standard sports suspension by a further 10 mm over the standard RS 6. A revised steering rack, with a reduced ratio of 14.3 for firmer steering feel was included, and resulted in a turning circle of 11.7 m. The brakes now included cross-drilled discs. The wheels were only available in the 9Jx19-inch '5-arm design' alloys, finished in "anthracite" (dark grey), with 255/35 ZR19 96Y XL tyres.
The car was available only as an Avant and was sold only in European markets. Visual differences for the RS 6 Plus included the "black optic pack", which consisted of black finish to the framing of the radiator grille, exterior window trims, tailgate lower trim, roof rails, and exhaust tailpipes. It quickly sold out once it was released (999 units total). The last three digits of the Vehicle Identification Number (VIN) are reproduced on a plaque inside the car, displayed on the centre console
C5 RS 6 in auto racing
The RS 6 was used in the North American SPEED World Challenge GT Series of auto racing for three years - 2002 to 2004, claiming the manufacturers' championship victory successively in all three years.[10] Once again, the special race derivative of the twin-turbo V8 engine was developed and manufactured in the UK by Cosworth Technology (now known as MAHLE Powertrain). However, the 2005 season proved difficult due to performance restrictions imposed on Champion Audi Racing by the Sports Car Club of America (SCCA), with Champion deciding to run a different wheel diameter, and the trade-off was reducing boost pressure.