Audi A8 Diesel 2006 Review

Another day, another diesel. The CARSguide team has tested so many oil-burners in the past few months that you would think diesel was the dominant fuel in Australia.

Well, it isn't and car companies still face a big battle to convince Australians that paying a premium to buy a diesel is worth it.

The image of diesel has moved forward from the days it was associated with smoking four-wheel-drives, but it still has a way to go.

Hoping to help change the image, several premium brands are importing diesel engines for some of their most expensive models, including 4WDs and sedans.

Audi is even importing a diesel version of its range-topping A8. This is the model that takes on the cream of the German limos, including the Mercedes-Benz S-Class and the BMW 7-Series.

The A8 range starts with a 3.7-litre petrol V6 for $169,950, then jumps to $204,500 for the 4.2-litre petrol V8.

So where does the diesel A8 sit in the range? Right on top of the regular models at $210,000.

Only the stretched A8s are more expensive. That is a lot of cash to cough up for any car.

But this diesel is different. It's not designed with fuel savings in mind. After all, the type of high-rollers who might buy this are about as interested in fuel prices as they are about price rises for a slab of VB.

The diesel donk in the A8 is about sheer force. It has 4.2-litres and eight cylinders assisted by two big turbos that spool-up to produce a healthy 240kW at 3750 revs — quite incredible for a diesel.

What is more impressive is the torque total — a whopping 650Nm.

To put that into context, the new 6.0-litre V8 in the Holden SS Commodore produces 530Nm and the Ford Falcon XR6 Turbo churns out 480Nm. This poke allows the big A8 limo, which weighs 1945kg, to dash from 0-100km/h in 5.9 seconds.

All the urge runs through a six-speed automatic and is fed to all four wheels.

Though the Audi boffins designed the engine with performance in mind, the fuel economy is also good. The official figure is 9.7 litres for 100km of city and highway driving.

This means owners could drive for 950km without having to stop for fuel.

Just as you would expect for a car that costs six-times the price of a base Commodore, the A8 TDI comes fully loaded.

It has all the safety gear with all the electronic assistance and a full-suite of airbags, as well as luxuries including a 17cm colour centre information screen with satellite navigation and TV tuner, eight-speaker premium sound system, leather seats, sunroof, xenon headlights that swivel to point around corners and a keyless start.

Another feature to delight the tech-heads is a fingerprint ID system that allows the car to recognise the driver and adapt accordingly.

ON THE ROAD

THE engine in the A8 is the best diesel we have driven. The burst of torque from the bottom of the rev range is simply brilliant.

It slings the A8 forward with such force that you look forward to the next stop, so you can go through the acceleration process again.

With the tricky variable geometry turbos working hard to smooth out the power delivery, the diesel surge runs all the way to the red-line.

The turbos pause only slightly before turning on the punch, a long way from the turbo lag that some smaller diesel engines still have.

Fuel consumption is not fantastic compared with many smaller diesels, but is excellent when you consider how potent the engine is.

The fuel economy figure we achieved on the test ran from about 8.5 litres/100km on the highway to 11 litres when pushed.

The automatic transmission is well suited to the punchy diesel and you hardly notice it.

You can, of course, use the paddles on the steering wheel, which shout "gimmick". The paddles are next-to-useless because the gearbox over-rides the driver and changes up anyway, even when the automatic is flicked into manual mode.

And with 650Nm of torque on tap, it is not as though you are going to have to work the gears to extract enough punch from the engine.

The A8 has exceptionally light steering, which is nice when you are cruising around town or trying to park in tight spaces. The downside is that it is too light if you ever feel like getting sporty on a twisty road, and there is virtually no feedback through the wheel for the driver.

The big German's adaptive air-suspension works quite well. It depends on your taste, but we found the standard suspension setting a touch too firm and the Luxury setting was too soft over any types of bumps.

The system absorbs most bumps with ease but, strangely, some small things such as cats-eye reflectors seem to send a jolt through the aluminium body.

When it comes to creature comforts, the A8 excels. Lots of things help out in everyday driving but many are there just to be shown off to friends.

The centre control screen is super-crisp, thanks to high-resolution colour graphics, and the MMI (Multi Media Interface) is the best control system in a luxury German car.

Seat comfort is excellent and there is a mass of interior space, including in the huge boot. The only thing missing from the cockpit is heated seats. They are optional, but should comes standard on such an expensive car.

THE BOTTOM LINE

The storming diesel engine is simply stunning and makes diesel make sense, and we'd pick it over the V8 petrol.

SCORE: 80/100

FAST FACT

This is the first time Australian customers can order an A8 with a diesel.

SPECS

$210,000 as tested

ENGINE: 4.2-litre V8 turbo-diesel with two VTG turbochargers

POWER: 240kW at 3750 revs

TORQUE: 650Nm at 1600-3500 revs

TRANSMISSION: Six-speed automatic with sports shift, all-wheel-drive

BODY: Four-door sedan

SEATS: Five

DIMENSIONS: length 5062mm, width 1894mm, height 1444mm, wheelbase 2944mm, tracks 1629/1615mm front/rear

STEERING: Speed-dependent rack and pinion

FUEL TANK: 90 litres

FUEL TYPE: Diesel

FUEL CONSUMPTION: 9.7 litres/100km

WEIGHT: 1945kg

SPARE TYRE: Full-size spare

BRAKES: Discs all round

TYRES: 255/40R19

SAFETY GEAR: Anti-skid brakes, electronic stability control, eight airbags

WARRANTY: Three-years/unlimited km

STANDARD FEATURES

Airconditioning

Cruise control

Alloy wheels

Climate control

Leather seats

Parking sensors

Automatic wipers

HOW IT COMPARES

Mercedes Benz S500: 79/100 (from $253,900)

BMW 750i: 73/100 (from $213,500)

Audi A8 4.2 (petrol): 78/100 (from $203,000)