The power of diesel

The petrol-powered Audi TT coupe.

It is perhaps a sign of the times that Audi general manager Glynn Tulloch used the launch of the petrol-powered RS4 sports sedan to talk about the next range of diesel models.

Over the next few months, Audi will launch A3 hatchbacks, A4 and A6 sedans and wagons, and an A8 sedan, all using diesel power. They will mostly cost the same as petrol equivalents.

Audi already has several diesel models, all using V6 engines. The new range will introduce more V6 units, along with a 2-litre four-cylinder diesel for the A3 and a 4.2-litre V8 diesel for the A8.

Tulloch and his researchers reckon Audi is on the right track with its upcoming diesel line-up. Does he see a long-term future in New Zealand in high-end diesel cars?

"Maybe not a long, long term," he said. "Trying to make the diesels comply with EuroV emissions standards is getting more and more difficult and involves huge costs.

"But over the medium term, yes I do - principally because they have solved the performance issues."

Diesel and petrol engines in European passenger cars have to meet strict Euro IV emissions before they can be approved for sale in the European Union.

Euro IV was introduced in January 2005 and becomes fully effective in January 2007.

Euro V comes into effect for trucks in October 2008. A Euro V standard for passenger cars has yet to be set, but legislators are aiming for a maximum of five parts per million of sulphur in diesel. New Zealand imposed a maximum of 50ppm in January.

Tulloch says diesel sales suffer from a perception of them being smelly and lacking power.

"Certainly the research we have conducted suggests that is a big barrier for our buyers anyway," he said

"They just don't understand what motoring writers understand, that the performance of the cars is incredible. They think diesels clatter around in four-wheel-drives. Their perception of diesels is 10 years old, because most of the diesels they see are 10 years old.

"So what we have done is introduce higher-performance diesel versions with quattro (all-wheel-drive). We see these models as the key to opening up that market."

Long-term, Tulloch sees a shift away from diesel engines into small capacity petrol units using superchargers and turbochargers.

Audi parent Volkswagen has developed such an engine, a 1.4-litre unit putting out 125kW (170bhp) and returning 7.5 litres/100km (38mpg).

The V8 engine in the RS4 is the first non-turbo unit in the RS range. Previous models have had twin-turbocharged powerplants but Audi wanted to move away from the lag inherent in boosted engines. The direct-injection 4.2-litre V8 in the new model has a compression ratio of 12:5.1 and revs to 8250rpm, up about 1000rpm over the previous RS4 engine.

It develops a maximum 309kW (420bhp) at 7800rpm and 430Nm of torque at 5500rpm and drives all four wheels through a six-speed manual gearbox. Around 90 per cent of torque is available between 2250-7600rpm.

The new engine is joined by a suspension system borrowed and improved from the RS6, which is more resistant to pitch and roll and is said to iron out the ride on broken surfaces.

Also new is the Torsen (torque-sensing) all-wheel-drive quattro system. The previous system split drive 50:50 front-rear under normal conditions. The new one splits it 40:60, favouring a rear-drive bias. The RS4 is priced at $159,900.

No word on the price of the new Audi TT coupe due in New Zealand later in the year. The soft-top roadster is expected to arrive in 2007.

The second-generation TT adopts lightweight aluminium construction, new engines and a thoroughly reworked chassis, says the carmaker. The sharp new styling, credited to young Spanish designer Jorge Diaz, was previewed on Audi's Shooting Brake concept unveiled at the Tokyo motor show last October.

The car is bigger and rides on a longer wheelbase, but the big news is the body is now fashioned predominantly from aluminium rather than steel. Audi claims the change sharpens handling and provides the TT with a more responsive feel.

The TT will be available with two engines: a turbocharged, direct-injection 2-litre four-cylinder driving the front wheels and a 3.2-litre direct-injection V6 driving all four.