The second-generation RS 6, later called the Audi RS 6 5.0 TFSI quattro (Typ 4F) was based on the Volkswagen Group C6 automobile platform and was launched in September 2007 at the Frankfurt Motor Show. With factory production starting in December 2007, it was available in Europe from the same date, and began to be exported elsewhere in 2009. The total production run of the C6 RS 6 was 8,000 units, with 6,500 of these being Avants and the remainder saloons. The RS 6 was not available in North America, leaving the Audi S6 as the top performing trim there. (The unpopularity of wagons made it unlikely that the RS 6 Avant would be imported, and although it had been rumoured that the RS 6 sedan would be offered in the United States,[12] nothing came of this as the RS 6 importer could not clear US regulations).Production of the C6 RS 6 ended in the third quarter of 2010.

The RS 6's 5.0 L (4,991 cc) V10 engine produced 426 kW (579 PS; 571 bhp) at 6,250 to 6,700 rpm and 650 N⋅m (479 lbf⋅ft) of torque from 1,500 to 6,250 rpm, 52 kW (71 PS; 70 bhp) and 150 N⋅m (111 lb⋅ft) more than BMW's 5.0L V10. As of January 2010, the RS6 was Audi's single most powerful car ever, and positioned the car ahead of its closest competitors, the BMW M5 and the Mercedes-Benz E63 AMG in terms of engine output, both of which have naturally aspirated engines. However the estimated price of the RS 6 sedan in 2010 was $160,000 USD (another source quotes $126,000 USD in 2009, making the RS 6 perhaps too expensive for the United States market[11]) which set it apart from the performance variants of other executive cars: the MSRP of BMW M5's was $85,700 USD, of Mercedes-Benz E63 AMG's was $87,700 USD, and of Audi's own S6 was $78,025 USD

Official performance figures for the Avant: 4.6 seconds for the 0-100 km/h (62.1 mph) sprint, 12.7 seconds 0-200 km/h (124.3 mph), and top speed is electronically limited to 250 km/h (155.3 mph), with a factory option to de-restrict the top speed to 274 km/h (170.3 mph). In standard form, CO2 emissions are rated at 333 g/km. The saloon reaches 0-100 km/h (62.1 mph) in 4.5 seconds.

The C6 RS 6 Avant was launched in April 2008, and the four-door saloon/sedan was available from August 2008. Constructed from steel in a monocoque (unibody) design, the RS 6 uses lightweight aluminium for its front wings (fenders) and bonnet (hood).

Visually, the RS 6 differed from the related S6, having flared front and rear wheel arches (fenders), harking back to the original Audi Quattro, to allow for a wider wheel track. It also had no front fog lights to allow for larger frontal air intakes (for the two side-mounted intercoolers (SMICs), and additional radiators). The ten (per side) front light-emitting diode (LED) daytime running lights (DRLs) are located within the main headlamp housing on the RS 6 in order to increase the size of the air intakes, whereas similar LEDs (but five per side) on the related S6 are found adjacent to the fog lamps in the lower front bumper. LED lighting technology was also used in the rear lights. The RS 6 also included adaptive headlights, which swivel around corners in conjunction with steering wheel movements. The facelifted Audi A6, released as a 2009 model, received similar front and rear-end LED lighting styling to that pioneered on the RS 6.

Luggage capacity, measured according to the VDA 'block method' in the Avant ranges from 565 litres (19.95 cu ft), to 1,660 litres (58.62 cu ft).

The engine (parts code: 07L, identification code: BUH) of the RS6 was what Audi claimed to be the first all-aluminium alloy even firing 5.0-litre (4,991 cc (304.6 cu in)) 90° V10 twin-turbocharged ("biturbo"), Fuel Stratified Injection (FSI), with a dry sump lubrication system. This engine is related to the naturally-aspirated V10 found in the Audi R8, S6 and S8, but the RS 6's engine has around 400 unique parts.

The engine has four valves per cylinder, with chain-driven double overhead camshafts, and variable valve timing for both inlet and exhaust camshafts. Charged intake air is cooled by two side-mounted intercoolers (SMIC)s. The engine is controlled by two Bosch DI-Motronic MED 9.1.2 engine control units, which act as 'master' and 'slave': two ECUs are required due to the high revs the engine can achieve. It also uses mapped direct ignition system with ten individual direct-acting spark coils, an electronic drive by wire throttle (Bosch "E-Gas"), cylinder-selective knock control, and cylinder bank adaptive lambda control, utilising eight lambda sensors.

A total of seven radiators and four electric cooling fans are needed to cool the engine and related components under the aluminium bonnet of the RS6.

Drive output passes through a ZF 6HP28A six-speed tiptronic automatic transmission. The gear ratios are: 1st: 4.171, 2nd: 2.340, 3rd: 1.521, 4th: 1.143, 5th: 0.867, 6th: 0.691, with shortened shift times, with "Dynamic Shift Programme" (DSP) and "Sport" mode. It has paddle-shifts mounted behind the flat-bottomed steering wheel, similar in design to the Audi B7 RS 4. The gearbox is set by default, in conventional automatic mode, to delay up-changes during acceleration, and change down earlier to maximise engine braking. Downshifts in all modes of operation include the Powertrain Control Module electronic control unit (ECU) "blipping" the Bosch "E-Gas" drive by wire throttle, for smoother shift shifts. The hydraulic torque converter includes a lock-up function in all forward gears and is able to completely disconnect when the vehicle is stationary, thus saving fuel.

Like all Audi "RS" models, the RS 6 is fitted with Audi's 'trademark' Quattro permanent four-wheel drive as standard. This version of the RS 6 uses the latest asymmetric dynamic 40:60 front-to-rear default torque distribution from the Torsen T-3 'automatic torque biasing' (ATB) centre differential. This latest incarnation of the Torsen Quattro, first seen in the B7 RS 4, can automatically dynamically apportion up to a maximum 100% torque to the rear axle, or up to 80% to the front, dependent on traction conditions.

The front and rear final drives are conventional "open" differentials (ratio 3.317) and use the Audi "Electronic Differential Lock" (EDL). EDL is a part, or "function", of the Bosch ESP 8.0 Electronic Stability Programme, which also includes "Anti-Slip Regulation" (ASR) traction control system. EDL does not 'lock' the differential in a traditional sense, but uses electronics to compare the speeds of the two wheels on an axle, and brakes any wheel that is sensed to have lost traction (by rotating faster than the opposite wheel, beyond normally accepted deviations). This braking of a slipping wheel has the effect of transferring torque across the axle to the other wheel, which is assumed still to have traction.

Like the previous RS6 and the B7 RS 4, this generation of RS 6 includes Audi's "Dynamic Ride Control" (DRC) Sports suspension system. The system is mainly mechanical, using a pump to provide additional pressure in the diagonally linked dampers (shock absorber) during cornering, to counteract rolling and pitching. The system can dynamically adjust the stiffness at each damper constantly to maintain both a comfortable ride and a high grip. In this version, it has a three-way level control, selectable from the Multi Media Interface controls.

The steering system includes rack and pinion speed-dependent "servotronic" power steering, with a ratio of 12.5, and a turning circle of 12.2 metres.

The standard brakes on the RS 6 are cross-drilled, radially vented, and floating iron discs. At the front they are 390 millimetres (15.35 in) diameter and 36 mm (1.417 in) thick, clamped by gloss black six-piston fixed Brembo monoblock alloy calipers incorporating the "RS" logo, and at the rear they are 356 mm (14.02 in) diameter and 28 mm (1.102 in) with black single-piston floating calipers and an integrated electro-mechanical parking brake linkage. The parking brake serves doubles as a full emergency brake whilst the car is in motion, by applying maximum braking effort to all four wheels, resulting in activating the Anti-lock Braking System (ABS).

Optional "Audi ceramic" Carbon fibre-reinforced Silicon Carbide (C/SiC) composite front brakes are available, only with 20-inch wheels, which use 420 mm (16.54 in) diameter by 40 mm (1.575 in) thick drilled, vented, and floating SGL Carbon composite discs, with grey painted eight-piston fixed Alcon monobloc alloy calipers with the "Audi ceramic" logo.

Irrespective of the type of disc construction, all brake discs are mounted via high strength steel mounting pins which connect the 'working' surface of the disc to lightweight alloy disc hubs.

A specifically 'tuned' "sport-biased" Bosch ESP 8.0 Electronic Stability Programme is standard, and includes Anti-lock Braking System (ABS) and Electronic Brakeforce Distribution (EBD), and Brake Assist (BA). This ESP system has three user-selectable settings: "ESP-on" - the standard default full protection mode, "ESP-sportmode" (which turns off the ASR and EDL traction functions), and "ESP-off" (which fully disables all 'stability' and 'traction' related functions).

Standard wheels (in the UK) are 9.5Jx20-inch '5-segment-spoke' design alloy wheels running on 275/35 ZR20 102Y XL (eXtra Load) tyres (rated at 850 kg (1,874 lb) per tyre), with official supplies being either Pirelli P-Zero Rosso or Dunlop SP SportMaxx GT. No-cost options are 9.5Jx20 '7-arm double spoke' design (identical style to B7 RS 4), or 9Jx19-inch '10-spoke' design alloys with 255/40 ZR19 Michelin Pilot Sport PS2 tyres.

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