A serious rival to the BMW 5 Series, Mercedes-Benz E-class and one or two others. If you can live with the slightly extrovert looks, you'll love the driving experience. Used car ownership is rarely this satisfying.

The smiles on the faces of Audi executives at the 1997 press launch carefully hid a touch of nervousness. Their latest A6 was the first to be designed from scratch wearing the badge - its predecessor was a lightly re-touched and re-named 100 - and the striking shape of the latest car could have alienated as many buyers as it attracted. It didn't. Even though business buyers in BMW 5 Series and Mercedes-Benz E-Class territory are notoriously conservative, the A6 had to be different to offer a real alternative. And it was, particularly in four-door form. Did a saloon really have to look like a saloon? Or could it be a touch more provocative with a roof line more akin to a sporty coupe? Characterful? Even in-your-face? Audi said 'yes' and the executive establishment decided the same. This A6 became a relatively common sight, giving its German rivals a run for their money on the British showroom floor, executive car park and motorway. So there are plenty of fine examples on used forecourts, too.

AUDI A6 HISTORY

Sleeker, lighter, safer and more spacious than its 100/A6 predecessor, Audi's senior executive express pulled into Britain in May 1997. The range was relatively simple with even the starter engine an excitable 1.8-litre four-cylinder turbo but the 2.4-litre V6 proved most popular. Like the larger 2.8, the 2.4 came with manual or automatic transmission, both with five speeds, and the self-shifter also offered Tiptronic clutchless manual operation at the driver's whim. The 1.8 had a more conventional four-speed auto and early 2.8s offered the choice of two wheel drive or quattro 4WD. Trim was either a lavish 'base' specification including twin airbags and climate control air conditioning or SE with alloy wheels, trip computer, front centre armrest and numerous other enhancements. Subsequent changes were discreet - put a personalised plate on your used A6 and the neighbours could think it's one of the last of line 2004 cars. Late 1997 saw the arrival of a 150bhp 2.5-litre V6 turbo diesel engine, with or without quattro 4WD, while the Avant estates arrived in May 1998, matching the saloons model for model. The mighty 295bhp 4.2 V8 quattro saloon debuted (with the A8's engine) in February 1999 and a 230bhp 2.7-litre V6 turbo saloon followed in June. Around this time the 2WD 2.8s were dropped, a clever new six-speed CVT 'Multitronic' automatic gearbox was introduced and interior fabrics and equipment were slightly revised. Late in 1999, the twin-turbocharged 4.2-litre V8-powered 340bhp S6 flagship auto-only model made its debut. Early in 2000, TDI quattro models were replaced by a 2.5 TDI quattro Sport variant with power up from 150 to 180bhp. 2001 saw a further revision to the A6 range. The 'double radiator grille' that previously only adorned the range-topping eight-cylinder A6 models was adopted across the range as were clear glass headlamp covers, whilst the standard lights were increased in size. The rear lights came in for a makeover too, with the reversing lights made almost cylindrical in appearance, and visible tailpipes made an appearance. The engine and transmission options multiplied. Two new petrol engines were available; the 2.0-litre 130bhp four-cylinder unit and the 3.0-litre V6 that developed 220bhp. The 2.4-litre engine gained 5bhp to 170bhp. Big revisions were made in the provision of diesel engines. Out went the 115bhp 1.9-litre TDI engine, replaced by the gutsier 130bhp, and in came a 2.5-litre V6 TDI unit developing 155bhp, slotting in beneath the muscular 2.5-litre TDI 180bhp engine that headed up the diesel range. In summer 2002 the 155bhp 2.5-litre diesel received a small boost up to 163bhp. At the same time the Sport variants were given a boost to their equipment list. The grand finale for this A6 came in the spring of 2004 with the unveiling of the RS6 Plus Avant, a limited edition car with 480bhp. The next generation A6 was on sale by the summer of 2004.

WHAT DO I GET FOR MY MONEY?

Sleek looks, great engines, a well-sorted chassis and top-notch active and passive safety systems are all found here. If you want more luggage space, check out Avants; for icy driveway grip, look at quattros. The equipment tally is complete too. Perhaps more significant, however, are the little touches. There are no fewer than 20 different interior lights and the seats are composed of several layers of various softness on a firm base so that they feel pliable but supportive on longer journeys. Every model has an electronic differential lock (EDL), plus ASR traction control (and ABS of course). If that's not enough, the options list offered a dictionary of acronyms - EBD, DSP, VTG and so on. Plus ESP, an electronic stability programme that, in panic situations, automatically decelerates selective wheels separately, preventing the car from skidding and fishtailing. To be honest, if you habitually find yourself in situations where ESP is likely to be of use, the A6 may not be your sort of car. All the high-tech gadgetry in the world can't hide the fact that it's front, rather than rear wheel drive, the class norm. Rear-driven cars are supposed to be more rewarding if you push them to the limit, a point proved by equivalent BMW 5 Series models, but refuted by the surprisingly dull Mercedes E-class of the same era. The A6 lies somewhere in between.

WHAT PRICE AM I LOOKING AT?

A6 residuals match the 5-series these days but, even so, there are some good deals to be had by canny used buyers. Don't concentrate on 1.8 turbo models too much because, although performance is fine, they're not as smooth and refined as V-engined A6s. However, you could pay little more than £4,300 for a 97P example that cost over £23,500 new. The 2.4-litre V6 does a better job of filling the A6's big engine bay and deserves its popularity. Pay around £4,500 for a base 1997. The 99S-reg SE saloons start at about £5,500 and estates are around £700 more. The more powerful 2.8-litre V6s start at about £4,800. These first 97P-reg cars offered the quattro transmission as an option (pay about £800 more) but it will have been standard from around 99V on. Though 1.9-litre fours range from £5,300 to £14,300, the pick of the turbo diesels is the 150bhp 2.5-litre V6, priced from about £5,600 on 97R plates. The estate is a great car for easy driving and the economy is spectacular for such a big vehicle. Better yet, it offers a 180bhp quattro 4WD alternative, priced from under £11,000 to around £16,000, which is well worth a search. The rare flagship 2.7 turbo V6 and 4.2 V8 quattro saloons date only from early 1999 and start from £6,600 and £8,500 respectively.

WHAT SHOULD I LOOK OUT FOR?

Not too much, really. There have been some tales of niggling unreliability but nothing too serious. The quattro system is reliable and well proven but it's best not to allow a local spannerman to fiddle with it. The complexity of the car should be enough to ensure you insist on an A6 with a cast-iron service history and, at this stage, Audi dealers are still likely to have the best examples. The premium they charge may be well worth your peace of mind. Interiors are hard wearing and well designed, much like the rest of the car. As for corrosion, with an Audi you're pretty safe.

HOW DOES IT DRIVE?

The performance is certainly more than adequate; both at the pumps (where the 1.9-litre TDi averages 40mpg) and on the test track - where even the 1.8T makes 60 in 9.4s on the way to 136mph. To be fair, however, V6 power suits the car better. The 2.4-litre unit is impressively refined and far less frantic, recording 9.1s and 141mph. Stretch if you can to the gorgeous 2.8 V6, 2.7T or V8 4.2-litre models which, in desirable quattro form, answer tractional questions that rivals haven't even thought about. This A6 is certainly a lighter, more agile car than its predecessor and feels it to drive. Audi claims a 35kg reduction in weight compared to the previous model - one reason why the fuel consumption figures are around 7% better across the range.

BY GRAEME ROBERTS

PARTS INFORMATION

(based on a 1999 1.9 TDI SE Saloon - ex Vat) A clutch assembly is around £150. Front and rear brake pads should be about £65 a set. A radiator is about £140, an alternator about £235 and a starter motor £160.