Audi RS6 (C5) | PH Used Buying Guide

Solidly built, fast and still different class. Welcome to the layer cake, son…

By Tony Middlehurst / Sunday, December 6, 2020

Key Considerations

  • Available for £9,000
  • 4.2 V8 twin turbo, all-wheel drive
  • Sub-five-second 0-60 times
  • Better to drive than early road tests might have you think
  • Well-built and still looks great
  • Not cheap to run

Search for a used Audi RS6 here

OVERVIEW

Movie director Matthew Vaughn might well consider 2002 to be the best year of his life. For a start, that’s when he got hitched to supermodel Claudia Schiffer, plus he was also making a very cool Brit gangsta flick called Layer Cake. This allowed him to give a starring role to a car that had dropped onto the motoring scene like Hulk jumping into a tin bath from a tenth-floor window.

In Layer Cake’s opening credits, Daniel Craig and his mate can be seen blatting away from a cobbled mews house in London in an Audi RS6 Avant before motoring on to Stoke Park golf club, as previously immortalised in Goldfinger by the other James Bond. Vaughn didn’t bother to put a bogus number plate on that Avus Silver RS6, so today we can see that its MOT expired in April 2016. It was in apparently fine health a year earlier, with just 68,000 miles recorded, so it’s probably still sat in a private collection somewhere. Hopefully someone here on PH will know exactly where, but even if it’s never seen again its place in history is assured.

As, in a more general sense, is that of all C5-generation RS6s. This car played a major role in legitimising the purchase of stupidly quick cars for family use. When it was launched in the UK in autumn 2002, the twin turbocharged 4.2-litre V8 RS6 Avant was the world's fastest estate car. It was the perfect choice for a handy geezer who needed to move henchmen, guns and ammo around the country in a rapid and stealthy manner, or just for someone who liked the sound and feel of a well engineered German thoroughbred with top-notch mechanicals. 

The RS6 (which also came as a saloon) was densely packed even before you started loading it up with whatever the tools of your trade might be. Forty valves, eight cylinders, two turbos, four cats, permanent Quattro four-wheel drive with locking Torsen centre diff and electronic diff lock, Tiptronic transmission, independent four-link front and double-wishbone rear suspension, hydraulic Dynamic Ride Control, eight-piston Brembo front brake calipers, it had the lot. It was as if Audi had told a gaggle of interns to scurry off to the parts warehouse, collect all the smuttiest items from the Quattro GmbH parts shelves, and give them to the A6 team with a hastily scribbled good luck note.

Estate body shapes traditionally cleaved through the air more efficiently than saloons, and because they were perceived as practical they were easier to get past the tightest household budget scrutiny, so it was no surprise that the first RS6 was an Avant. Remembering that Audi had already built the RS2 Avant as a joint venture with Porsche and the B5 RS4, it was odd that BMW and Mercedes didn’t see the RS 6 coming. Mercedes’ only counter was the old (and 90hp weaker) W210 E55 AMG, but even so they were in a better position than BMW, who had nothing. Their E34 M5 Touring had been discontinued seven years earlier, and the solitary E39 M5 estate that they had built for evaluation never made it into production. Even if it had, the M5 engine would have come up 44hp short against the 444hp Audi, which also had the significant benefit of four-wheel drive to help it achieve a road-churning four-second 0-62mph time.

For 2003, Mercedes bolted a supercharger onto its new W211 E55 AMG to give it a decent shout against the Audi, but another four model years would elapse before BMW mustered up its second (and most probably last) M5 Touring, the Europe-only V10-powered E61. By then however the moment had passed and the M5 estate was quietly discontinued in 2010. Not until 2011 would Mercedes offer the option of four-wheel drive on its E63 AMG Estate.

Back to Audi. Today’s RS6 has 600hp, but don’t make the mistake of thinking that a near-20 year old C5 with 444hp must feel dog slow by comparison. It doesn’t feel slow in comparison with anything, even in 2020, and if you really feel you need 600hp, that’s perfectly attainable. As it stands, the flow of urge from what was Audi’s most powerful engine – developed in collaboration with Cosworth – is addictive and gigglesome. The age and weight of the car allied to the business-suit image of the A6 estate only add to the other-worldliness of the motor’s ability to supply relentless and convincing grunt, singing to 7,000rpm while delivering a typically-turbo high torque line across a big rev band.

That torque plateau is even wider in the Plus model that was built in the last few months of the RS6’s life in 2004. With additional intercooling and a new ECU, it generated 473hp over a slightly narrower rpm range, reducing the 0-62 time to 4.6sec or less in the right conditions. Sold in Avant form only, the Plus was still limited on top speed, but to a less restrictive 174mph. It rode 10mm lower on its Sports Suspension Plus and five-arm anthracite alloys, had bigger drilled brakes and steered a little more precisely than the regular RS6 courtesy of a revised rack. 999 were built (you’d think they might have made another one), and there was a plaque on the centre console ahead of the shifter to tell you which one you had.

SPECIFICATION – AUDI RS6 (C5) (2002-04)

Engine: 4,172cc V8 40v biturbo
Transmission: 5-speed Tiptronic automatic, all-wheel drive
Power (hp): [email protected],700-6,400rpm (Plus [email protected] 6,000-6,400rpm)
Torque (lb ft): [email protected],950-5,600rpm (Plus [email protected],950-6,000rpm)
0-62mph: 4.9 secs (Plus 4.6)
Top speed (limited): 155mph (Plus 174mph)
Weight: 1,840kg (Avant 1,865kg, Plus 1,880kg)
MPG (official combined): 19.3
CO2: 350g/km
Wheels: 9×19
Tyres: 255/35
On sale: 2002 – 2004
Price new: from £58,800 (Plus £66,675 in 2004)
Price now: from £9,000 for high-milers

Note for reference: car weight and power data is hard to pin down with absolute certainty. For consistency, we use the same source for all our guides. We hope the data we use is right more often than it's wrong. Our advice is to treat it as relative rather than definitive.


ENGINE & GEARBOX

The RS6’s V8 is unusual by modern turbocharged standards in that it sounds great both inside and outside the car. There is a small amount of turbo lag but not enough to diminish the sensation of urgent throttle response and whipped cream acceleration in every gear.

The RS6 is a halo vehicle. Halo-level maintenance is required to make it give of its best. Basic servicing should be done every 12 months at least. Oil changes (preferably using quality oils like Castrol Edge) should be carried out every 5,000 miles, with timing belt/water pump changes ideally every three years or 35,000 miles. While the front of the car is off you may want to think about replacing the O2 and cam positioning sensors, voltage regulator and starter.

Seals, pipes and cam cover gaskets can all leak, as can intercoolers, risking turbo failure. MAFs, lambda sensors, manifolds and engine mountings can break. On the plus side, this is not a direct injection engine so there’s much less of a problem in carbon buildup that can really affect cars like the B7 and B8 RS4. Plus-spec hot weather auxiliary radiators are a popular mod. 

The transmission is a five-speed ZF Tiptronic automatic with lock-up torque converter working with a quattro permanent four-wheel drive system that uses a Torsen T-2 dynamic automatic torque biasing (ATB) centre diff to apportion engine torque between the front and rear axles. Rumours were put around in contemporary road tests that the ZF box gave you a throttle blip on downshifts, but as far as we’re aware that function was never available. The Dynamic Shift Programme (DSP) did make use of trendy fuzzy logic to adapt shift times for any driver’s style, and you did have manual control through the steering wheel-mounted paddles or the console gearshifter, but in either manual or auto mode this is an old-tech box and changes, though slick enough, will feel relatively sluggish to anyone coming from a more modern auto.

On that tack, only five gears might seem a bit sparse in these days of ZF nine-speeders but the RS 6 has more than enough torque to carry the trans and in these sometimes over-complicated times you might even appreciate the idea of a smaller gear stack. Some believe think that pulling back for change-ups and pushing forward for downchanges would have been more intuitive than the opposite setup provided in the RS6, but it’s just a matter of getting used to it. The gearbox fluid and filter should be changed every 40,000 miles.

Even with diligent maintenance, however, the torque converter does have an unfortunate reputation for failing at higher mileages. Early signs of that are what you might expect: jarring changes, odd revving patterns, or even complete disconnection under power. If you have the luck of the Irish, a fluid change might rectify it, but if you don’t, you’ll be staring at a £3,500-£4,000 rebuild invoice. Gearbox selector switches go too. Some have carried out manual gearbox conversions but the feedback on those isn’t that great.

With an official combined fuel economy figure of 19.3mpg and considerably lower figures than that popping up on the trip computer as a matter of course, even when you thought you were taking it easy, the process of filling the RS6’s 82 litre tank (preferably on high-octane juice) will soon become grimly familiar. Tuning won’t improve that experience, but it will make the RS6 even more fun. A stage 1 remap will take you over 500hp and boost torque to 470lb ft+. Stage 2 will yield 540hp/516lb ft, stage 3 600hp/575lb ft. Aftermarket exhausts, for example Milltek ‘race’ downpipes, sound amazing for these.

Wagner intercoolers, hybrid turbos, custom tubular manifolds, raising the rev limit, lowering the TC lockup point – the options are off the scale for these. MRC has a good name for RS6 tuning. Don’t expect any of it to be especially cheap though. And mind that gearbox: it’s already near its torque limit at the standard spec. Beefed-up converters are available.

CHASSIS

The RS6 sat 20mm lower than the standard car on the fully independent four-link front, double wishbone rear A6 suspension. Its spring rates were 30 per cent stiffer, with compression damping up by 40 per cent.

At the time of the C5’s launch, there were the usual complaints about dead Audi steering, but again if you’re coming into one of these from a more modern car with numb electronic steering, you’ll wonder what those complaints were about. The three letters that do genuinely pall the experience of any C5 RS6 owner are ‘DRC’. Audi’s Dynamic Ride Control system made its debut on this, the first RS6. In simple terms, it was a hydraulic network of pipes, a pump and two control valves that altered the pressure to individual dampers so that they could provide the right response to changing conditions, reducing body roll during cornering and maintaining a level pitch under extreme acceleration and deceleration.

When it was working, DRC did a great job of flattening out the UK’s pocky roads. The other advantage, in theory at least, was that it was built around relatively simple mechanical componentry rather than the complicated electronics that companies like Mercedes were using to achieve the same end.

Unfortunately, Audi’s hardware turned out to be rubbish. Depending on how many of the damper units sprang a leak, which they almost invariably did, one or both of the diagonally-controlling central valves (front left with rear right, and vice versa) would also had to be replaced, at an astronomic cost. In fact, independent Audi specialists were soon warning that if there was a failure on one side, the other side of the axle should be replaced too, so effectively you’d end up replacing all four corners even if only one had gone.

Legal action in the US resulted in DRC being designated as not fit for purpose and free replacements were supplied. As usual, there wasn’t such a happy resolution in the UK, but given that the replacement units in the US were just as likely to fail as the old ones, maybe it wasn’t too much of a loss. If you enjoy courtroom dramas then by all means take a chance on an RS6 with the DRC system still in place. Otherwise, stick to cars that have had conventional Koni or Bilstein suspension put in.

The bushes on an RS6 or on any 16-18 year old performance car that weighs almost 1.9 tonnes will be saggy unless they’ve already been sorted by the previous owner. Pound for pound, there are few jobs that will provide as much enhanced driving value as the fitting of new bushes to a big old performance car. New anti-roll bars from the likes of Hotchkis do no harm either. The RS6's weight will always be evident, especially on sharp corners, but you’ll never tire of the Quattro system’s ability to fire you out of those corners with commendable neutrality. In addition, the C5 feels a lot narrower on B-roads than the 2020 RS6, nicely closing the gap between theoretical and useable performance. A good bit of effort needs to be put in if you want to get a grudging flicker of recognition from the traction control light.

Stamping on the brake pedal will quickly haul you back to reality but if you plan on plenty of hard driving you might want to improve the stoppers. Fitting the 390mm cross-drilled discs and six-pot calipers from a C6 is a common upgrade. Expect the front brake pads to last between 10,000-15,000 miles, with a new set of discs and pads coming in at well over £1,000 and that’s if you’re looking hard. All braking and tyre consumables are more expensive than those of a standard A6 Avant.

ABS control modules on a C5 RS6 are known to malfunction. A combined pump and ECU/module will cost around £200, or you can get your existing one rebuilt.

BODYWORK

One of the RS 6’s most appealing features is the styling, which is a brilliant integration of big wheelarches, skirts, deep bumpers, twin exhausts and RS6 badgery into the regular A6 estate’s sober lines. The Plus distinguishes itself from normal RS6s by a ‘black optic pack’ exterior featuring black grille, windows, tailgate, roof rails, and tailpipes.

Although Audi’s designers did a good job on the looks, they didn’t quite manage to kill off the A6 spectre of blocked bulkhead drain holes or perished pollen filter seals, both of which will allow water to soak the carpets and potentially cause expensive damage to the electronics beneath. Additionally, the main fuses behind the coolant expansion tank can be attacked by rust as a result of drain blockages.

Obviously, these are old cars now, and fast ones too, so be extra vigilant on your checks for paint bubbling and non-Audi like body panel gaps suggesting poorly executed accident repairs. Try not to biff anything with your RS6 as you’ll struggle to find a used replacement front bumper for less than £1,000, and there’ll be paint required on top of that.

INTERIOR

There’s a strong whiff of premium inside an RS6 even now thanks in large part to the high quality of the switchgear and trim, most of which came straight from the standard A6. If any of the panel pixels start to disappear, new or used panels are easily found. Some of the connectivity options that were proudly offered back in 2002 might not be so easily remedied when they go phut, but then again do you really need a TV with Teletext? 

Hindsight allows us to mock unforeseen obsolescence, of course, but some of the RS6’s other interior options are still very much worth having, like the Recaro CS carbon-back heated seats which added £3,000 to the cost of an RS6. Those who have tried them say that they transform the car.

The Plus model got a plush mix of Alcantara and leather along with heated front and rear Recaro sports seats, a five-inch TV screen and xenon headlights. In any RS6, make sure that everything works – Bose stereo, seats, windows, feeling of superiority.

Some cars had a solar panel sunroof. The juice from this would power fans to circulate air through the car when it’s parked, which was useful on a hot day. Not so usefully they do tend to steam the windows up on a rainy day but it’s nothing that a quick blast of aircon won’t clear. Unlike on some other cars, the solar roof doesn’t trickle-charge the car’s main battery. Battery conditioners are therefore worth considering if you’re going to be leaving the car locked up and unused for more than a few days at a time.  

PH VERDICT

450hp seemed like an insane amount of power in 2002, especially when it was shoved up an estate car. Nowadays, that figure would be sneered at by those expecting at least 600hp from their performance estates, but the fact is that in isolation, the C5 RS6’s 444hp is more than enough to blow your kilt right up.

Few would nominate the RS6 as the finest driving tool ever made. They don’t involve you in the same way that a V10 C6 might, but they do move you, and at a hell of a rate, too. The wagons in particular are fast, practical, and comfortable. All RS6s are well built, and most important of all, they’re still horny looking, especially in the flesh. The interior won’t feel dated to any but the most critical. There aren’t many more characterful tools to take you and three or even four of your mates to the Nürburgring. The more the merrier when it comes to chipping in for petrol because fuel economy was, and still is, very poor.

In fact, RS6s chomp through anything that’s susceptible to wear, up to and including the gearbox, so only buy cars with full service histories, give yourself a budget for bills, and enlist the help of specialists for advice. Warranties for these cars are not always easy or cheap to secure. Providers may choose to refurbish rather than replace busted transmissions, and they may even bounce a DRC suspension claim right out of the room, so box clever. Always choose a leggy example with a strong transmission over a lower-mileage car without a clear history of good gearbox maintenance.

Having said that, you may not have the luxury of being able to make such clear-cut buying decisions in the UK because not that many RS6s were sold here in the short production run, which lasted just two years from July 2002 to September 2004. The production numbers, if you’re interested, were 870 Avants, 271 saloons and either 70 or 77 Plus models, depending on what bit of the internet you believe.

As usual, the Avant was far more popular than the saloon among British buyers, outselling it by more than three to one, partly because they look better to most but also because they were cheaper to insure. Avants are slightly more expensive than saloons, despite and indeed because of their extra popularity when new. Start points for decent cars will be around £11,000 for a 100,000-mile saloon and around £14,000 for a well maintained, lower mileage dealer Avant.

We did find an 88,000-mile 2003 Avant for just £10k, but its MOT expired in December 2019. We also saw a 150,000-mile MOT’d Avant for £9,000. There were no Plus RS6s on sale at the time of writing. When they do come up, they attract quite a hefty premium. Expect to pay £25k or more for one.

In the PH Classifieds we found a 2003 saloon and a 2002 Avant for £11,500 each. The silver saloon has 103,000 miles, the essential full service history and some MRC tuning which we’re assuming is a stage 1 remap as it comes with a 500hp dyno printout. The Avant is a private 92,000-miler in blue with a recent full engine and gearbox service and a full MOT.

Nearer to £17k is this Mugello Blue 2003 Avant with 83,000 miles. Again, it comes with a very comprehensive and impressive sounding service history including a recent belt change and gearbox check, plus a Milltek exhaust to raise merry hell. 


Search for a used Audi RS6 here

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