Guide: Audi C5 RS6
Background
Audi’s high performance RS line originated with the B4-based RS2 Avant launched in 1994.
Like the fabled Quattro of 1980 to 1991, the RS2 programme was initiated by Ferdinand Piech who ultimately became the head of Audi and transformed the company into a serious rival for BMW and Mercedes-Benz.
The B4 RS2 was a collaboration between Audi and Porsche. Piech was the grandson of Ferdinand Porsche but had left the family firm for Audi in 1971.
Although Audi sold more examples of the expensive RS2 than had originally been expected, a like-for-like replacement was not immediately forthcoming. After RS2 production stopped in 1995, it was another four years until another RS-badged Audi broke cover.
That car was the B5-based RS4 that Audi unveiled at the Frankfurt Motor Show in September 1999.
As per the RS2, the RS4 was based on Audi’s junior platform and was offered in estate-bodied Avant configuration only.
Unlike the RS2, the RS4 was developed by Quattro GmbH in collaboration with English company, Cosworth Engineering. Production ran from May 2000 to September 2001.
Six months after the RS4 had been discontinued, Audi launched their third iteration of the RS line at the Geneva Motor Show in March 2002.
The new RS6 was based on Audi’s mid-range C5 platform used by the A6 and high performance S6 models. It was another technical collaboration between Quattro GmbH and Cosworth. Once again, supercar rivalling performance with an inconspicuous appearance was the order of the day.
The C5 platform had arrived in 1997. It was the second generation A6 produced and was offered with a plethora of petrol or diesel engines and saloon or estate bodywork. A high performance S6 flagship was added to the range in 1999 which came with a 335bhp version of Audi’s normally aspirated 4.2-litre V8.
The S6 was subsequently toppled when production of the wild RS6 got underway in July 2002. It was the first RS-badged Audi to be offered as an estate and a saloon. It further broke with convention on account of its Tiptronic-style automated-manual gearbox. The C5 RS6 was also the first Audi RS to be offered for sale in North America (albeit in saloon trim only).
The labour-intensive construction process took place at the Quattro GmbH plant in Neckarsulm. Despite a high list price, Audi planned to build a run of 6000 cars over a two-year period.
Chassis
The RS6 was based on the same pressed steel bodyshell with aluminium forward section as other V8-powered models in the A6 range. A 2759mm wheelbase ensured the cockpit was extremely spacious.
Independent suspension was via a four-link arrangement at the front and double wishbones at the rear. Anti-roll bars were fitted at either end. For the RS6, stiffer springs and dampers were installed which dropped the ride height by an additional 20mm over the S6 variant.
Another new feature was Audi’s hydraulic Dynamic Ride Control system that altered the pressure to individual dampers so that they could provide the right response to changing conditions. This had the effect of reducing body roll during cornering and maintaining a level pitch under extreme acceleration and braking.
The brakes were also uprated for enhanced stopping power.
The 321mm ventilated front discs and Lucas twin-piston calipers from the S6 were dropped in favour of massive 365mm discs with eight-piston monobloc Brembo calipers. At the back, the 269mm discs with single-piston Lucas calipers from the S6 were switched to 335mm diameter with ATE calipers.
Gloss black paint was used for the uprated RS6 calipers and those at the front were further customised with an RS logo.
ABS and Electronic Brakeforce Distribution were standard along with power steering.
Alloy wheels came in two sizes: 19 x 9-inches for most markets and 18 x 8.5-inches for North America.
As usual for the C5, an 82-litre fuel tank was installed under the rear seat.
Engine / Gearbox
Engine-work was outsourced to Cosworth Engineering.
In S6 trim, Audi’s normally aspirated all-alloy DOHC V8 with its five valves per cylinder produced a respectable 335bhp at 7000rpm and 310lb-ft at 3400rpm.
In the transition to BCY trim, Cosworth added a pair of KKK K04 turbochargers and two large pressure-loss optimised air-to-air intercoolers.
Other equipment included variable inlet valve timing, Bosch Motronic ME 7.1.1 engine management, fully sequential electronic multipoint fuel-injection with intake manifold-sited fuel injectors and a mapped direct ignition system with solid state high voltage distribution that used eight individual single-spark ignition coils.
Four catalytic converters were fitted (two close-coupled primary cats and two underfloor main cats) along with four heated oxygen sensors which managed the lambda control.
For reasons of longevity, the compression ratio was dropped from 11.0:1 to 9.3:1.
Displacement was an unchanged 4172cc thanks to a bore and stroke of 84.5mm and 93mm respectively.
In this configuration, the RS6 pumped out a formidable 444bhp at between 5700rpm and 6400rpm. A mighty 413lb-ft of torque was developed from 1950rpm all the way up to 5500rpm.
The only gearbox that could handle such a figure was ZF’s five-speed automatic 5HP24A unit with lock-up torque converter in all forward gears. A Tiptronic function enabled manual control through the steering wheel-mounted buttons or the console gear lever (forward for up, backwards for down). A Dynamic Shift Programme (DSP) adapted shift times to driving style.
Transmission was through a permanent four-wheel drive system with Torsen T-2 dynamic Automatic Torque Biasing (ATB) centre diff to apportion power between the front and rear axles. There was also an electronic diff lock.
Bosch’s ESP 5.7 Electronic Stability Programme formed part of the ASR traction control system.
Bodywork
Cosmetically, the RS6 differed to the S6 on account of its front bumper assembly, rear apron, deep side skirts and doors without moulded lower sections.
Unlike the S6 Saloon, the RS6 sedan was equipped with a rear spoiler.
The RS6 Avant came with a bigger spoiler mounted at the trailing edge of the roof than was fitted to the S6 Avant.
RS6 grilles were given a distinctive diamond pattern and the intakes housed in the corners of the front bumper were significantly enlarged.
The sporty new rear apron house a unique oval tail pipe on each side.
To identify the new model, RS6 badges were added to the primary intake grille and on the tailgate.
Silver roof rails were standard on the Avant.
Interior
Most of the RS6 interior trim was imported from the A6 / S6.
Instrumentation comprised a large RS6-branded rev counter and speedometer, either side of which was an oil temperature gauge and ammeter. In the centre were more small read outs for water temperature and fuel. Underneath these was a digital read out for the onboard computer and an array of warning lights.
The three-spoke steering wheel was trimmed with a perforated leather rim and also came with an RS6 logo.
Leather was used to upholster the Recaro seats and door inserts. The roof lining was trimmed in alcantara suede. Aluminium inserts were fitted throughout.
Other standard equipment included satellite navigation, air-conditioning, electric mirrors, electric windows and a high end Bose audio system.
Options
Audi offered a range of optional extras for the RS6. They included carbon-backed Recaro seats, heated seats, xenon headlights, parking sensors, heated folding exterior mirrors, mobile phone preparation, a multifunction steering wheel, electric steering adjustment, tinted glass, sun blinds, a CD changer, carbonfibre cockpit inserts, dual zone air-conditioning and an upgraded Navigation Plus system.
There were also two types of sunroof: a standard tilt/slide type and a solar panel type.
Weight / Performance
In Avant trim the RS6 weighed 1865kg while the Saloon was 25kg lighter (1840kg).
Both variants had a 0-62mph time of 4.9 seconds and a top speed limited to 155mph.
In de-restricted form, in excess of 180mph was likely possible.
RS6 Avant Plus
For the last six months of production, European customers were offered an even more powerful run out model loaded with extra equipment.
The RS6 Avant Plus was introduced in April 2004 and sold in Avant form only. It came with two additional radiators behind the side-mounted intercoolers (as fitted to RS6 bound for hot climates). There was also a re-mapped ECU that liberated an additional 30bhp.
The power output was now 473bhp at between 6000rpm and 6400rpm. In terms of torque, 428lb-ft was developed between 1950rpm and 6000rpm.
Chassis upgrades included 10mm lower ride height, cross-drilled brakes, a more precise steering rack and anthracite 19 x 9-inch five spoke alloy wheels.
Outside, special Sprint Blue paint was a no cost option. The RS6 Avant Plus also came with xenon headlights and a black optic pack for the grille, windows, tailgate, lower trims, roof rails and tail pipes.
Cockpits were a special mix of alcantara and leather. Heated front and rear Recaro seats were standard along with a five-inch TV and carbonfibre inserts.
999 examples of the RS6 Avant plus were built, each of which came with a numbered plaque on the centre console ahead of the gear lever.
Although weight rose by 15kg to 1880kg, the 0-62mph time was two-tenths-of-a-second quicker (4.7 seconds). Top speed was restricted to 174mph.
End of Production
RS6 production lasted from July 2002 to September 2004.
In total, 8081 were built of which circa 1200 were exported to North America. About 10% of total production is believed to have gone to the UK in right-hand drive.
Text copyright: Supercar Nostalgia
Photo copyright: Audi - https://www.Audi.com
