Audi A8 4.2 TDi

5:24pm Wednesday 19th April 2006

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AUDI'S recent win at the Sebring 12-hour race didn't exactly set the sports pages of English newspapers buzzing recently. Maybe that's because the race was held in America.

Maybe it was because Audi has won the event, held on a Florida airfield, every year since 2000.

So another victory is hardly the stuff of legends.

Except this year was different.

This time the Audi team turned up with a revolutionary and little-tested car and came away with an historic victory.

Motorsport boss Dr Wolfgang Ullrich said the victory was right up there with the world debut of the famous Audi Quattro four-wheeldrive rally car.

And it wasn't just Dr Ullrich celebrating.

Back home in Germany company bosses were positively ecstatic.

They had good reason to be.

The Audi car that had just blown away the competition thousands of miles away was very, very different from any racing car before it.

It may have looked like just another endurance racer but beneath the aerodynamic bodywork there was a turbodiesel engine purring away.

The car's debut victory marked the first time a diesel had seen off petrol-powered competition in an international motorsport event.

Indeed, the high-octane world of motorsport was the last redoubt for petrol power, diesel having long since won the battle for hearts and minds in car showrooms.

But the Audi win showed that diesel technology can now compete blow-for-blow with petrol racing engines - and it can win.

It also demonstrated how deadly serious Audi is about diesel engines and just how good it's technology really is. This was driven home to me again a few days later when I slipped behind the wheel of the whisper-quiet A8 TDI.

The all-new 4.2-litre V8 is currently the world's most powerful production diesel engine.

In fact, it has a set of figures that wouldn't have looked out of place in the back of an Italian supercar just a few years ago.

Power is up from 275PS in the outgoing 4.0 TDI to a whopping 326PS at 3,750 rpm.

More impressive still, the maximum torque figure of 650 Nm is available all the way from 1,600 rpm to 3,500 rpm.

Even in a big, heavy flagship like the A8 that kind of serious clout produces terrific performance - 062mph in 5.9 seconds and an electronically-limited top speed of 155mph.

Despite feeling every bit as quick as those figures suggest, the A8 can still return excellent fuel consumption giving a range of almost 600 miles on a single tank of fuel.

If there's a more accomplished engine currently fitted to a production car I've yet to drive it.

But that's getting ahead of myself.

Let's start again, which is exactly what Audi had to do when it decided to replace the widely acclaimed 4.0-litre V8 TDI used in the old A8.

That engine made its debut in 2003 and for a long time it reigned supreme as Europe's most powerful diesel V8.

It also proved to Audi how right the concept of a dieselpowered luxury saloon was: pretty soon after its debut the car had a 71 per cent share of the market segment.

To make real progress beyond what was already a remarkable engine, the Audi TDI development team had to design an entirely new powerplant.

It came up with a V8 that had more capacity in a unit that was smaller, lighter, smoother and stiffer than anything that had gone before.

The extra power is generated by twin turbos that use variable vanes for greater efficiency at all revs.

With the turbos rotating at a crazy 226,000 revs per minute there's absolutely no lag when you put your foot down - the A8 just goes whatever the gear and wherever the revs.

From behind the wheel the Audi boasts several innovative technologies to make life easier.

Advances in electronics have made things possible that would have been science fiction just a decade earlier.

Take something as innocent looking as the key. Inside the fob is an electronic pulse generator that flashes a signal to a proximity sensor in the door as you approach.

If the signal is the right one the doors open the moment you touch a flush-fitting button on the handle. You can lock or unlock just one or all four doors via the car's electronic nerve centre.

This advanced system also releases the steering wheel and switches on the ignition as you settle into the comfy leather seats (electrically-adjustable, naturally). Then you can start the engine by press a switch.

Sticklers for protocol can, of course, start the engine in the normal way by turning the key in the ignition lock.

There are other surprising gizmos. A fingerprint recognition system (I'm not making this up) memorises your favourite seating, heating, mirror and steering positions.

When you get in everything is fine-tuned and adjusted just as you like it. Up to four fingerprint templates can be stored.

Adaptive cruise control (where fitted) uses a hidden radar to prevent the A8 burying itself into the back of slowermoving traffic, intelligent air suspension raises or lowers the body depending on the speed and road conditions and adaptive lights can help 'see' around corners by switching on an extra reflector as you are turning the wheel.

And I haven't even got the space to do more than mention the aluminium space-frame chassis, the excellent singlebutton multi-media interface (BMW take note, single-button interfaces can work if you don't make them ridiculously complex), the six-speed Tiptronic automatic transmission, the solar-panel sunroof, the auto locking boot and, best of all, the digital TV system that lets you watch Sky while you wait for the toddler group to wind up on a wet Thursday morning.

As a technological tour de force the A8 takes some beating. It is a car that can carry five adults and a large amount of luggage in complete comfort.

With the V8 purring away up front and cruise control taking care of your licence, it really is possible to cross countries in this car without breaking into a sweat.

There is one area where German efficiency let me down.

The cup-holder in the front console may look good but it's next to useless - a soft drink was dumped in my lap at the first roundabout - not good.

The dual-branch exhaust system has been re-tuned to create a sporty snarl Audi considers to be the ideal accompaniment to its new car's character.

To be certain that a sporty snarl doesn't turn into an annoying drone, the exhaust uses five silencers to ensure cruising is done in almost total silence.

New engine mounts and an extra layer of insulation make the A8 the most refined diesel in the world by a significant margin.

The ride - the only area where the old A8 fell behind a BMW 7-Series - is now as settled as a Jaguar but should you need to press on the big Audi handles remarkably well for such a heavy car.

In addition to the many passive safety features (an immensely strong body, fourwheel drive, adaptive suspension etc) the A8 represents a new benchmark for active safety kit.

Specification
Engine cc: 4.2 V8
Power: 326 PS
Max speed: 155 mph
0-60mph: 5.9 sec
Combined mpg: 29
Insurance group: 19
For convenience: Everything you can think of - and quite a lot more.

For safety: Dual stage airbags, run flat tyres.