Lockdown has put car retail into deep hibernation, but not everyone has given up. The private seller of this week's Pill hasn't done much more than slip a Corono-gag into the advert text - "outrun COVID19 with your whole family, and the dog" - but that still earns a few bonus points for trying. While we wouldn't recommend trying to outpace a non-bacterial pathogen, the rest of that sentence speaks to what has always been the core appeal of any RS-badged Avant model - the combination of effortless pace and proper practicality. That was true even when this RS6 left the factory making 450hp, but it has since been tuned since to produce a claimed 540hp. Not bad for any car, and especially not a 16-year old estate.
While both S and RS badged Audis have featured semi-regularly in Brave Pill, this is the first example of one of the most important ones to make it here. The C5 was the first RS6, but also the first RS model that sold in sufficient volumes worldwide to persuade Audi to give its quattro GmbH division much more freedom in choosing cars to benefit from RS-level transformation.
It was also a modest triumph for British engineering. Audi had bought Cosworth Technology in 1998, this being the road car engineering side of the famous motorsport business. Cosworth had already created the high-output version of Audi's twin-turbo 2.7-litre V6 that powered the B5 RS4, and was charged with a similarly muscular transformation for the RS6. This would use the same base engine as the existing S6 - a 4.2-litre 40-valve V8 - but would have to deliver a sizeable supplement over that car's 335hp output.
Working together, Cosworth and Audi engineers created a twin-turbo installation with two intercoolers, and also decided on a stronger block (which was cast in the UK). Engines were assembled and tested by Cosworth before being dispatched to Deutschland and united with heavily modified S6 bodies - these featuring both heavily flared arches and significant structural reinforcement.
While the RS4's V6 had to be worked hard to deliver its best, the brief for the RS6's powerplant was to be all-muscle. On that, it delivered: the peak 428lb ft of torque was available from just 1950rpm - very low for any petrol engine in those days - and this gave the RS6 effortless shove. So while the Avant's 4.6-second 0-62mph time was impressive enough, half a second quicker than a contemporary 996 Carrera 4S, from behind the wheel it was the Audi's ability to pile on pace without breaking sweat, seemingly regardless of engine or wheel speed, that was its defining characteristic.
It was a point made on the RS6's UK press launch in Scotland in 2002. Or, more precisely, on the way to it - awkward deadlines meant some magazines had been given the cars before the event took place. My job was to return one of them in time for the first wave of attendees to have a go. I made a pre-dawn start from London and made Newcastle early enough to opt for a cross-country route instead of the dull grind of the A1. On an empty stretch of the A696 I was making progress, as police officers and feature writers liked to put it, without realising quite how much progress I was making. Near Otterburn I glanced at the RS6's speedometer to see a number so unlikely that my brain converted it from km/h to mph and discovered it was still naughty. The issue being I had been looking at the mph scale all along...
Beyond its ability to deliver huge pace and vaporize licenses the RS6 was more tool than instrument. The powertrain was happy to trundle, and although the five-speed autobox wasn't the snappiest transmission the engine's huge torque meant that was never an issue. But driven harder the Quattro drivetrain was all about business, delivering huge traction without any playful hinterland. Grip was effectively total until it wasn't, although in tighter corners the RS6's 1870kg mass and nose-heavy weight distribution made it keener on the verges outside corners than the apexes within. Ride quality was also well short of plushness, with the standard Dynamic Ride Control a hydraulic system that fought pitch and lean by increasing damper pressures, but which could turn it harsh on rough roads at higher speeds.
While some people did buy the RS6 saloon, it always felt like the under informed choice, and was outsold by the Avant by increasing margins year-on-year. Beyond raw pace the four-door was lacking when compared to the sublime talent of the E39 BMW M5, or the refinement of the W211 Mercedes E55 AMG that launched in 2003.
But the RS6 Avant possessed a truly unique USP, certainly until the E55 wagon arrived in 2005. This was the fastest estate car in the world, one with the ability to carry both family and gear at a cross-country pace you'd need a helicopter to better. Regular users of the German autobahn network soon grew used to the sight of a well-laden RS6 whistling past at impossible speeds with kids in the back, even while wearing a roof box or ski racks. It didn't take long for early buyers to realise that the official 155mph speed limiter didn't cut in until well past 170mph.
This didn't come cheap, of course. Costs on an RS6 can feel closer to sprinting than running, especially given its ability to deliver the sort of bills that leave you unable to sit down for several days. The C5's maintenance regime is closer to thoroughbred than family lugger, with 5000 mile oil change intervals and 35,000 mile/ three year timing belt swaps. Hard use pushes mpg to single figures - with high teens being a good average - and the car will also devour tyres, brakes and flimsier suspension components with relish. The DRC dampers are also a well-known failure point, to the extent they are often replaced by passive coilovers.
It's not a car that can be run on a stingy budget, but our Pill doesn't seem to have been. The vendor reports a recent cambelt and radiator, a service last December and the welcome presence of fresh-ish Goodyear rubber. The power increase came courtesy of an ECU upgrade from long-established fettlers MTM, fitted in 2014 alongside a stainless exhaust and high-flow catalysts. Truthfully, 540hp isn't a fire-breathing state of tune for one of these. Other changes seem limited to black-painted original 19-inch alloys - easily reversed - and an aftermarket infotainment system in place of the factory 'nav. Delving into the MOT history reveals repeated advisories for an oil leak, and warnings of some corroded suspension components.
So it's not a minter, but it's not priced as one. For £9995 our Pill is one of the cheapest C5 RS6s in the country (that's £83,000 less than the unoptioned list on a new one) and looks to have years left to give to an owner prepared to do right by it. While the successor C6 generation car switched to a V10 engine, the fact the more recent C7 and C8 iterations have both used twin-turbo V8s with similar displacements and power outputs to our Pill suggests the original recipe was the best one.
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