AT first glance - especially from the hind-quarters - it could be an A8.

But closer examination and with the help of a reference for a dimensional check you realise it is the smaller brother, the latest Audi A6.

The visual similarity is considerable, but this is the saloon that must do battle with some of best all-rounders in the world - BMW 5 Series, Merc E-Class and our own home-grown Jaguar XF.

Already well-established across most sectors, the middle-executive class has proved a hard one to crack for Audi.

I drove the A6 3.0 TDI SE S tronic which meets 530d, E350CDI and XF 3.0D head-on in terms of price, power and size.

The new model, out only months, has been on a strict diet to cast off pounds in the interests of economy and efficiency.

Despite packing a 2,967cc six cylinder diesel which whacks out 242bhp, it manages emissions of 158g/km putting it into Band G for tax purposes. This means an official fuel consumption of 47.1mpg - even real life driving results in around the 40mpg mark.

We've got to remember an exec saloon isn't just about looking swanky and wafting up and down the motorway at speed.

Many of the buyers will actually have to carry people - full-sized ones - in the back as part of their jobs.

This is where there has been a major improvement in the current A6. Leg and headroom are now generous enough to elevate it to a class-leader.

The cabin itself is beautifully finished and appointed in beige Milano leather (a £750 extra on the test car) and the flowing fascia with easy-to-read dials is a treat.

Plenty of stowage space and cubbies and even expanding string pockets in the front seat-backs...a nice practical retro touch.

The boot holds 530 litres of luggage, slightly above class average and is sensibly shaped to make the most of the area.

The 3.0-litre diesel is silky and coupled to an S-tronic automatic gearbox delivers a smooth flow of power, and some impressive figures - 62mph comes up in an unflustered 6.2 seconds, making it the swiftest model in its class.

Top speed is just over 150mph. Mechanical noise is barely noise is barely noticeable which tends to emphasise the amount of sound intrusion transferred from the tyres and road.

Road-holding and handling with help from fat eight inch-wide low profile tyres and the quattro four-wheel drive system - a great advantage in winter - is of a high standard and offers tenacious grip. Less impressive is steering which feels over-light and somewhat detached from the road beneath.

With a price tag of £39,100 you expect to be indulged with a few of life's comforts and the A6 doesn't disappoint.

Front and rear sensors, cruise control, leather seating, Bluetooth and dual climate control are all standard. But head-up display is £1,450 extra and an upgraded Bang & Olufsen sound system will set you back a considerable £6,300.

Classy-looking and surprisingly economical to run, the A6 is able compete on even terms with the world's best. In some areas it leads the way.