BMW expresses reliability fears with new turbo engines

The Bavarian marque suffered teething issues with its new Class One challenger in last week's Lausitzring test, with Bruno Spengler losing track time on Tuesday with engine cooling issues and Joel Eriksson suffering electronics problems on both Monday and Tuesday.

Eriksson proved to be BMW's fastest driver in the test with his best time on Wednesday, ending up sixth in the combined timesheets, 0.715 seconds slower than Audi driver Robin Frijns.

"I believe that something will happen this year that we haven't seen in the DTM for a long time - that drivers with technical problems will retire,” Marquardt told Motorsport.com.

"The DTM has delivered excellent results on the track with close races and wheel-to-wheel-battles, but we haven't seen any technical problems for a long time. But with all the new systems this will happen again in one or another race."

Marquardt went on to explain the challenges of cooling associated with the new four-cylinder engines, which generate more power than their predecessors and more wasted heat energy.

“Previously you had a car that was symmetrically designed for a naturally-aspirated V8," he said. "Now you're installing a much smaller four-cylinder turbo, but with a very crucial component: It is asymmetric. You have a hot side and a cold side.

"If you look at the car, from the driver's point of view you have a lot of space on the left side because there's nothing [there]. And on the right side you have the turbocharger, the exhaust system and everything else that goes with it.

"It's very narrow there. That's why the heat balance and the air supply are a real challenge. You're actually blocking the air flow you need with the hot components.

"You need to get a very good static shield against the heat, and when the car is moving, you still need to get a good flow of cooling air. To get both under one roof - with all the parts, you have a lot of standard parts like suspension, shock absorbers and so on - was a really big thing.

"There were also solutions that didn't work. We had to do it again."

While enjoying a smoother week of testing than BMW, Audi didn't have an entirely trouble-free Lausitz test, as Jamie Green's running on Wednesday was cut short by problems.

Audi Sport boss Dieter Gass admitted the Ingolstadt manufacturer is not yet in a position where it can relax on the reliability front.

"By switching from the four-litre eight-cylinder to the two-litre four-cylinder with 100bhp more the load on the engine is already extreme," he said.

“Of course we'll do everything we can to make sure we're reliable, but we don't have the data that enables us to be at ease with it and say, 'That's alright'."

René Rast, Audi Sport Team Rosberg, Audi RS 5 DTM

Photo by: Audi Communications Motorsport