There's a good range of petrol engines, including a 2.0-litre turbocharged four-cylinder unit, a 2.8-litre V6, and a supercharged 3.0-litre. The V10-engined S6 is amazingly fast, but the more popular diesel units include two 2.0-litre units, plus a sweet 2.7 and a potent 3.0 V6. The A6 is a big car, and while you might think it needs a big engine to shift it, in fact our favourite is the more powerful of the two 2.0-litre TDI units. It’s smooth, powerful, refined and economical.

Although the standard suspension offers a decent blend of comfort and control, it doesn’t cope with as wide a range of road conditions as the more sophisticated, more expensive air-suspension. With air added to the reassurance of traction-boosting four-wheel-drive, you’re getting close to the ultimate A6. With this set-up, the A6 changes direction sharply, resists roll and clings on well. In the S6, though, the ride is very firm, and the car is not as agile as you might expect.

Sporty the A6 may be, but refinement has not been overlooked; the car is remarkably hushed up to motorway speeds. The 3.0T is the smoothie of the bunch, but all the engines, other than the 2.0-litre diesel, are impressively quiet, although the S6's V10 sounds great when you give it its head. The automatic gearbox changes gear almost imperceptibly, and the manual is much better than the one offered in the BMW 5 series.

The A6 is a bit cheaper to buy than the equivalent BMW 5 Series, but it can’t match the running costs of its rival. Emissions are generally higher than the BMW's, so you'll pay more in company car tax, but Audi’s latest engines have narrowed the gap in terms of fuel consumption (although the S6's V10 will drink fuel at a frightening rate if you use its full power). There’s little or nothing between the two in terms of resale values.

Everything has been polished to a level that marks this car out as one of the best-built executive estates of the moment – and better than some luxury cars. Audi reliability does not always match its standards of assembly, though.

The Audi A6 has an extremely stiff body. The saloon received a maximum five stars in the Euro NCAP safety testing, and every model is fitted with anti-skid and stability control, anti-lock brakes and six airbags. The A6 also scored strongly in security tests conducted by insurance body Thatcham.

There's a huge amount of steering wheel and driver's seat adjustment, so no one should have a problem finding the perfect driving position. Over-the-shoulder visibility is not brilliant, but you can specify reversing parking sensors. The dash is well laid-out and all versions have a rotary switch in the centre console used to control the various functions through a dashboard screen.

Audi has built a car that fills the gap between executive cars and true limousines. That means huge amounts of head- and legroom in the back. The boot is a huge 546 litres, too, and split-fold rear seats are available for longer items.

Even entry-level cars are well equipped with standard features such as cruise control, dual-zone climate control, electromechanical parking brake, a CD player, four electric window and MMi radio controls. S adds leather. S line versions have stiffened suspension, a sporty bodykit and bespoke cabin trim, while the high-performance S6 has a suitably lavish specification.