THERE'S only one word to describe the Audi SQ7 - incredible.

With 435 horsepower bursting out of a twin turbo V8 diesel engine and more torque than you get in Lewis Hamilton's F1 racer, the SQ7 is the most powerful SUV in the world.

And if the question is ‘Why?' then it is because Audi can.

Never forget they are masters of technology and created the first diesel car to win at Le Mans in 2006.

But that was with a purpose-built racing car, not an SUV - and the SQ7 is one of the biggest you can get weighing 2.3-tonnes. It can also seat seven, sits more than eight inches off the ground and has some credible off-road ability.

Creating this all-weather, family-sized supercar has involved some world beating engineering, not only to give the SQ7 such firepower but also to hold it in check.

The twin turbo on the huge diesel has been hooked up to an electric compressor to give boost from low revs.

That's bye-bye to turbo lag and hello to instant power - lots of it.

Open the throttle and the grunt blasts in with the drama of an enhanced roar from the four exhausts which decorate the rear of this monster.

It's all backed up with an eight-speed auto box, a multi-mode drive control and paddle shifters which can snap the SQ7 through the gears like a roadster.

The result is astonishing statistics for a car of this size with 0 to 60 flashing up in 4.8 seconds and the top speed electronically restricted at 155mph.

More electronics come into play to cancel out roll through corners and the grip from the SQ7 is astonishing, even when sitting on huge rims with masses of rubber.

Push it hard and the SQ7 will return around 25 mpg, drive it for fun and it's good for at least 30 to the gallon.

With stop/start and a coasting function included in the transmission Audi claims an official fuel return of 39.2mpg and a CO2 figure of 190g/km - and that's on 20-inch alloys.

Audi is fussy about which cars get its S classification and those in the know regard them with respect.

Normally the S badge is reserved for high performance petrol models but last year the S club grew to include a diesel with the arrival of the SQ5 V6 - a model based on Audi's mid-sized Q5 SUV.

Now comes the SQ7 - an upgrade of the latest Q7 launched last year - which pushes diesels into a new dimension and puts another feather in the Audi cap.

Where this super diesel engine will appear next is a closely guarded secret but it's guaranteed that it won't be confined to SUVs.

The thrill from the SQ7 can be taken even further with the likes of a sports differential and all wheel steering while standard finish includes bold body styling, a dominant matt-finished grille, shiny aluminium side bars and the characteristic quattro blisters around the wheel arches.

A subtle V8 T badge appears on each front wing, the brake callipers are flashed in red and there's an SQ7 badge tucked away front and rear but those are the only giveaways.

The SQ7 is priced from £70,970 and that puts the Audi super-SUV in the mix with upper echelons of BMW's X5, the Range Rover Sport and the Porsche Cayenne - all very special cars but none with such diesel muscle.

The SQ7 with its seven seat configuration is nicely practical and even fully occupied boot space is 235 litres - about the same space as you get in a Ford Fiesta.

In five seat set up that grows to 770 litres and with all seats folded the SQ7 takes on van-like proportions with the best part of 2,000-litres available.

Storage pockets and plug in points are accessible from all three rows of seats but the centre console in the front is little more than a wireless phone charging station.

High tech abounds. Audi's virtual instrument panel, a head up display and a sat nav system that is linked into the cruise control and LED lighting system can all be fitted.

In some situations the car is smart enough to drive itself and the cleverness extends even to knowing whether it's raining when it adjusts speed limit alerts accordingly in countries which enforce lower speeds in bad weather.

However, such equipment is off the options list and kit out the SQ7 to the level that most will find acceptable for a premium SUV with world-beating features and you will be pushing the price through the £90,000 barrier.

That's top dollar but the SQ7 is top notch and a car which is out on its own when it comes to clout and prestige. In diesel SUV terms there has never been anything quite like it.