MOTORSPORT: Audi guarantees diesel future

The appeal of turbo-diesel engines to car buyers should rise in coming years as increasingly stringent emissions regulations drive up the manufacturing cost of petrol engines.

That’s the view of one of Audi’s most senior engine development experts, Ulrich Weiss, who also confirmed the Volkswagen luxury brand’s long-term commitment to growing the sales share of diesel engines globally including the USA and China, where petrol engines currently dominate.

“We believe this technology (diesel) must penetrate these markets because it does offer considerable advantages for our customers,” Weiss declared.

Weiss, who is Audi’s head of development for diesel engines, was speaking to motoring.com.au during a press briefing at the Le Mans 24-hour sports car race last weekend.

Audi uses a diesel V6 engine as part of the hybrid drivetrain of the R18 e-tron quattro LMP1 sports prototype, which scored a one-two result in the classic.

Weiss explained direct-injection petrol-turbo engines will require additional investment to meet rising emissions standards such as Euro 6 and beyond because they must filter health-damaging particulate matter.

“Currently the diesel engine has a big weight to carry because of the costs to the company,” Weiss explained. “That means the exhaust after-treatment system, the injection system is more expensive and the materials are thicker and so on.

“But with the discussion on the particulates on the petrol engine then this (cost) gap will be closed a little bit because clearly they have to work in this direction and that means they have to start with additional catalysts and so on and that means the petrol engine will get a little more expensive and the gap will be closed.

“At the end you always have this benefit that the diesel engine is more fuel efficient than the petrol engine and then the customer will give us the answer.”

Weiss said the fuel efficiency of diesel also meant it must continue to be part of the range because it would be vital to achieving fleet averages for fuel economy specified by future legislation.

“To reach the new standards regarding CO2 from the legislations and the average of fuel consumption from all the cars, you need answers beside the petrol engine, because only with petrol-driven cars you will not fulfil them. You need diesel engines and petrol hybrids.”

He admitted diesel-hybrids were also a future solution for Audi and to expect a diesel e-tron plug-in model in the future: “It is a question of economics, but the combination is one that will come.”

Further emphasising its commitment to diesel, Audi has also just shown a an RS 5 TDI concept powered by a new 283kW and 750Nm version of the company’s 200kW biturbo 3.0-litre turbo-diesel engine fitted with an electric compressor to eliminate low rpm lag.

Weiss said sporting diesels engines in RS models were a distinct chance for the future.

“The first responses we got (to the concept) are looking good so maybe we have a new type of market for these type of engines (diesel), which also means good work for me and my team.”

Weiss admitted diesel engines would never be able to match the high revving capability of petrol engines and that worked against it them as a sporting choice. However, he said that gap would be closed.

“We will not reach the revs of the petrol engine because the mass we have with the crankshaft is much bigger than compared with a petrol engine, but what we have done with the concept car is increased the rpm by about 500 to 1000rpm, which helps performance.

“This is the first step in this direction… but you will never see a diesel engine with 10,000rpm, definitely not.”

Weiss said the extra revs were eked out of the concept engine by reducing the mass of the crankshaft, con-rods and pistons, thereby improving their acceleration.

The electric compressor will debut in a production car in 2015, most likely the second-generation Q7 SUV. Weiss said it will spread beyond the 3.0-litre turbo-diesel to petrol engines of different capacities in the future.