Audi's effortlessly cool brand image might jar slightly with the unbridled extravagance of the luxury 4x4 sector but in no way can the company's Q7 offering be considered a shrinking violet. With over five meters of length, the capacity to seat seven and tipping the scales at nearly 2,300kg, it isn't small. Just be thankful there's an improved 3.0-litre TDI engine option to keep the running costs reasonably inconspicuous.

If the green lobby is to be believed, luxury 4x4s are devils incarnate, devouring the planet's virgin resources, trailing an acrid plume of toxic emissions and running over domestic pets wherever they go. It's true that big offroaders like Audi's Q7 don't do the environment many favours but neither do many other kinds of motorcar and if you opt for the 3.0-litre diesel model, you can drive it with a relatively clear conscience.

Diesel is big news in the luxury 4x4 sector. It fuelled 42% of all models sold in 2000, by 2004 this had increased to 67% and the trend has continued. It's not difficult to see why either. The 3.0-litre TDI Q7 can now return an improved average of 34.9mpg compared to 20.8mpg in the 4.2-litre V8 petrol version. It also emits 260g/km of CO2 compared to the V8's 326g/km. Just for the record, a humble Ford Mondeo 3.0-litre V6 saloon can only return 27mpg while a BMW 650Ci coupe gets 22mpg, so big 4x4s do not have a monopoly on hefty fuel bills. A Porsche 911 Turbo, meanwhile, pumps out 307g/km of CO2 and you'd need four of them to carry the same number of people you can get in a single Q7.

The 3.0-litre TDI diesel engine fitted to the Q7 is offered in various models across the Audi range and it's proven to be a strong performer. An exhaust gas recirculation system helps to deal with the extra nitrogen oxide and particulate emissions that diesels traditionally produce compared to petrol alternatives, while the common-rail injection system with piezo injectors ensures that combustion is as efficient as possible in the first instance. The 240PS maximum power output is available at 4,000rpm but the headline figure is the 500Nm of torque that's produced at just 1,750rpm. Thanks to this, the Q7 responds to throttle inputs at low speeds in a manner that defies its bulk.

"It was Audi who popularised 4x4 transmissions in road cars back in the early 80s"

Floor it, and the engine, along with its 6-speed tiptronic gearbox, will contrive to get you to 60mph in 8.5s. If conditions allow, there's also a 134mph top speed to be explored. The engine is noticeably noisier than the V8 petrol model but it's still very refined in the grand scheme of things. At 70mph it's the rustling of the wind around the Q7's A-pillars that provides the acoustic accompaniment but it's at a muted level that means the Q7 is virtually as refined as an A6 executive saloon.

Audi never knowingly pass up a chance to remind us that it was they who popularised 4x4 transmissions in road cars back in the early 80s and the Q7 features the latest version of the quattro system. It's designed more for on-road handling than extreme all-terrain action but the Q7 will still do far more offroad than most owners will want to do in their £40,000 SUVs. Torque is split 40:60 between the front and rear wheels via a Torsen centre differential. If slip is detected by the ESP stability control system, power can then be diverted with as much as 65% channelled to the front or 85% to the rear. Audi's adaptive air suspension system is standard on all Q7 models and this can be jacked-up to offer different degrees of ground clearance. 'Offroad' mode is 35mm higher than standard and 'Lift' mode is 25mm higher than that, giving a total clearance of 240mm. There's even hill descent assist and a trailer stabilisation system for owners looking to tow.

The Q7 handles very well on the tarmac with the weighty steering doing much to inspire confidence and no small amount of composure in corners considering the vehicle's formidable bulk. In fact, it's easy to forget you're piloting something quite so large until you glance in the rear view mirror and see the expanse of seating stretching out behind you.

Seven seats is the standard interior configuration for the Q7. Set-up in this way, the seating provides copious amounts of space for the front and middle row occupants but the rear seating is suitable only for small children or adults on short journeys. There's 330 litres of luggage space when the rearmost seats are folded into the floor and if they're likely to spend all their time in this position, you might like to consider the 5-seat version. Here the third row is deleted which means the load floor is lower and there's 775 litres of luggage space. It's also possible to specify a middle row of two 'comfort' seats comprised of a pair of separate chairs with an armrest come storage box in between. This in conjunction with the 3rd row delete option, opens up the possibility of four or five-seater versions of the Q7

It's indicative of the moneyed target market Audi have identified for the Q7 that the plushest S-Line trim level is accounting for over 70% of sales. The entry level 3.0TDI model costs £38,075 but the extra £2,500 it takes to upgrade to SE is mere pocket change to these affluent individuals and the £900 on top that's needed for the 3.0TDI S-Line is unlikely to be missed from their voluminous bank accounts. The standard Q7 looks fairly well-equipped with 18" alloys, rain sensing wipers, dark sensing headlamps, a CD stereo, cruise control, rear parking sensors and two-zone climate control. If you want leather, and most Q7 customers probably will, you'll have to step up to the SE.

The improved 3.0-litre TDI engine makes a lot of sense in the Audi Q7. It has more than enough grunt to move this substantial vehicle around the place and it keeps fuel economy at reasonable levels. Despite the Q7's impressive on-road dynamics, you don't come away from driving the 3.0TDI version wishing for the extra power of the V8. Which says it all really.

TOP 3 Q7 DEALS

The results below show the top Q7 deals on buyacar

	Audi Q7 3.0 TDI Quattro 240 5dr Tip Auto Off Road
	ETR	Mthly £604	Saving £2,699	Price £36,126
	Audi Q7 3.0 TDI Quattro 240 SE 5dr Tip Auto Off Road
	ETR	Mthly £646	Saving £2,899	Price £38,426
	Audi Q7 3.0 TDI Quattro 240 S Line 5dr Tip Auto Off Road
	ETR	Mthly £641	Saving £2,899	Price £38,426

typical 9.58% APR

PCP finance quote over 48 months,  10,000 miles pa,  deposit of £1000