It's not unusual for car manufacturers to endow cars that are nearing the end of their days with a few extra goodies to help clear showroom space for the arrival of a replacement model. Boxes of CD players, alloy wheels and floor mats get unearthed from the backs of factories, and contents are divvied out onto decrepit models in a vain attempt to clear floor space.
And, as I write in January 2005, a new Audi A6 estate, or Avant, is imminent, thus spelling the end for all incarnations of the current model, including the RS6. So it only seemed fitting to test the 'ultimate' version of the outgoing car. Nothing to do with fancying a go in a 174mph motor, you understand. So how did Audi decide it should polish off sales of the 450bhp, £60,000 estate? Um, by slapping an extra 30 horses under the bonnet and applying a set of attractive, if somewhat kerbable for a family car, aluminium wheels. Et voila, one £66,675 RS6 plus. Or rather, 999 RS6 pluses, for that is the production limit. Better than a set of floor mats and free front foglights, eh?
So, is it any good then? It's not bad, aye. Even from a distance it's fairly obvious that this de-chromed RS6 isn't like other A6 Avants. Those big grey wheels perfectly fill the arches, the ride height is dropped 10mm over the (already low) regular RS6 (as part of the free 'sports suspension plus' package, which includes firmer springs and dampers), and the blue colour of our test car is also unique to the RS6 plus, as are two other colours, silver and ebony black.
Inside, all RS6 pluses get carbon-fibre trim inserts, plus the exceptionally supportive and comfortable, electrically adjustable and leather Recaro seats you see pictured here; as well as a little plaque forward of the gearlever, on which each model's limited edition number is engraved.
The engine fires up with a menacing woofle, indicating that a great deal of air is being in- and exhaled by the twin-turbocharged, 4.2-litre V8; its gases featuring rather more carbon dioxide when exiting the new sports exhaust than they did on entry (to the sum of 350g/km, or half a tonne every 888 miles). Blame combined cycle fuel consumption of 19.3mpg for that one.
But what an engine. There's a little delay after one buries the throttle into the carpet, which may be turbo lag, but feels like much like any other auto gearbox's torque converter taking up the slack, and then the RS6 is off like a shot. 0-62mph takes just 4.6 seconds and that 174mph top speed is limited; without it, 200mph should be within reach. And because the RS6 plus weighs 1,865kg and feels it, you know serious forces are at work. That 480 metric horsepower (473bhp if one is entirely accurate) comes in at 6,000rpm, while peak torque of 413lb ft is available the entire way between 1,950 and 6,000rpm. So it doesn't really matter what gear you're in: bruising acceleration is just a foot-flex away.
Braking requires a firmer foot. Discs are new, cross drilled and ventilated both front and rear, while front calipers have eight pistons. With driver, passenger and maybe a spot of luggage on board, two tonnes of fast-moving estate car takes some stopping and these do the business with decent pedal feel and little fuss, save for the body shifting considerably forward on the suspension, no matter how firm the dampers.
Truth is, Audi couldn't have made the dampers any firmer - not with 35-profile tyres all round, at least. On the optional sports suspension, the ride's borderline acceptable for a car of this type. The standard RS6 is better, while (from memory) the latest M5 is better still; but the RS6 is one of several late Audis that have a ride and handling balance promising the latter at the expense of the former, but failing to deliver satisfactory levels of either. The RS6 plus's ride is sometimes harsh, while at nearly two-tonnes, it's never going to feel agile. It does have high grip levels though and steers with satisfactory precision, if devoid of much involvement. But B-roads and track days are not its - nor any other 1,865 kg estate car's - forte.
Smooth motorways or sweeping fast roads are more the RS6's thing, where it at least has (heated) seat comfort, good noise insulation, a superb sound system and an 82-litre fuel tank on its side. Even then, bear in mind that in-gear acceleration is best provided the Tiptronic gearbox is left in a specific gear rather than Drive, because in the time it takes the RS6 to rev and kick down, a following modern turbodiesel will already be impatiently baying to pass (though there's satisfaction to be gained in the ensuing seconds as they recede rapidly in the rear-view).
So, is it the ultimate sporting estate? In that it has superb seats, high grip levels and astonishing depths to its performance and can still carry the kids and the dog, yes. But bear in mind that a car with this performance will always demand some compromise: at the thick end of seventy thousand quid and with that borderline ride, the RS6 plus is still an indulgence.