The Audi Q7 is one of the biggest cars on the road. At more than five metres long, nearly two metres wide and 1.74 metres tall, it is as imposing as a prop forward. It combines the ability of an off-roader with the practicality of a people carrier and the luxury of a limousine.

Sitting on the stretched underpinnings of a Volkswagen Touareg (Audi is part of the VW group), the Q7 has the internal space of an aircraft hangar - complete with three rows of seats. And, unlike in some of its rivals, the rearmost seats are by no means a token gesture (Audi claims more leg-room than any other maker in the segment). As for the middle row, it is usually configured as a bench but there is the option of two individual seats.

All Q7s come well equipped but you’ll find that used examples usually contain plenty of optional extras such as DVD players and upgraded wheels. Always remember that it’s not worth paying a fortune for another person’s wish list. They may make the vehicle easier to sell but not more valuable.

Despite a hefty kerb weight of about 2½ tons, the Q7 feels nimble on the road. Much of that is down to its electron-ically controlled air suspension, which comes with three driver-controlled settings: automatic, dynamic and comfort. The results are impressive. As speed climbs, the Q7 settles lower on the road, reducing the drag caused by its bluff styling, and lowering the centre of gravity.

Taking the Q7 off road requires less driver input than changing tracks on the CD player. An advanced electronic stability program that combines traction control with a locking differential keeps the wheels turning, while an “off road” suspension setting raises the Audi an inch higher from the ground.

Propelling the Q7 is a range of excellent petrol and diesel engines. Most popular is a 3 litre turbodiesel producing 237bhp and powering the car from standstill to 60mph in a little over 8sec while still achieving 28.8mpg. Even more powerful is the 4.2 litre V8 TDI, which joined the lineup in July 2007; with an additional 85bhp and 560 lb ft of torque, it will outsprint a Golf GTI to 60mph.

Petrol power comes from either a 3.6 litre V6 or a 4.2 litre V8 unit. Both deliver plenty of pace but inevitably fuel economy is poor. The excellent build quality and variable service intervals mean they can go 19,000 miles between visits to a dealer, so do not be surprised to see scant evidence of stamps in the log book.

With the future of luxury 4x4s in doubt, the Q7 may well come to be seen as an automotive dinosaur by future generations. However, for the time being, it is one of the most spacious and best equipped you can buy.

OWNER’S VIEW
It’s a great motorway cruiser but a bit too big for some of the roads near my home. I think I’ll go for something smaller next time. Richard Fiennes,Brighton

NOTE THE FOLLOWING

ELECTRONICS All Q7s come with a pace-limiting hill descent mode, roll-over stabilisation system and safe-towing mode GEARBOX Six-speed tiptronic gearbox standard on all models
MMI Fiddly multimedia interface uses a rotary dial to govern in-car systems, including climate control and stereo
REAR SEATS When not in use, the third row folds into the floor of the boot, giving up to 2,035 litres of storage space

VITAL STATISTICS
MODEL Audi Q7 3.0 TDI S line
ENGINE 2967cc, six cylinders
POWER 237bhp
TRANSMISSION Six-speed tiptronic
FUEL 28.8mpg (combined)
CO2 260g/km
ACCELERATION 0-62mph: 8.5sec
TOP SPEED 134mph
COST NEW (2006) £39,900
TAX BAND G (£400 a year)

VALUES
MILEAGE 10,000 20,000 40,000
2006 (06) Trade £25,700 £24,450 £22,050 Retail £28,750 £27,500 £25,250

2007 (07) Trade £27,800 £26,400 £23,850 Retail £31,000 £29,500 £27,000

2008 (08) Trade £30,100 £28,550 £25,800 Retail £33,250 £31,750 £29,000

THE ONE TO BUY
Audi Q7 3.0 TDI S line 2006 06 with 20,000 miles. Pay £27,500 at a dealer or £25,500 privately

OR FOR SIMILAR MONEY
2006 06 Porsche Cayenne S
2006 56 Toyota Land Cruiser 4.2 TD
2007 07 BMW X5 3.0i SE
2007 57 Land Rover Discovery TDV6 HSE
2007 57 Mercedes-Benz R 320L CDI Sport

SAFETY The Audi Q7 scores only four out of five stars for adult occupant safety although four stars for child occupant safety is among the best in the class

SERVICING Variable interval: 9,000-19,000 miles

TAILGATE Electric motor to open and close the tailgate controlled from key fob

TYRES With either 18in or 20in wheels, replacement tyres are expensive

UPHOLSTERY Leather seats are standard on SE; S line models get grippy Alcantara inserts. Base models with cloth seats are rare