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09 June 2014 - 00:00

Road/rally cars: what's the difference?

This weekend, VW won the Rally Sardinia, Sebastien Ogier romping home in his Polo more than a minute ahead of his nearest rival. It was VW’s tenth WRC win on the trot.

All very impressive, but what does it all mean for our road cars? After all, Ogier’s all-terrain weapon doesn’t share one single part with the diesel Polo sat on your neighbour’s driveway.

But, says Dr Heinz-Jakok Neusser, VW’s Board Member for Development, there’s plenty of crossover between his firm’s rally programme and road-going offerings. Not in terms of physical parts, but in terms of philosophy. Gene-sharing, if you will.

“What we have learnt from motorsport is precise driving,” Neusser told TG in Sardinia. “Everything has to be precise from the reaction side. Steering, brakes, throttle. We are not pushing power, we are pushing performance.”

Neusser highlights the Polo rally car’s ability to accelerate out of a corner. Clever combustion processes are the key because, as a result of the air restrictor on WRC turbos, altering the actual turbo makes little difference. “We only have the chance to make more power by improving the combustion system and the [internal engine] friction as well. And this technology has transferred directly to the road car.”

The torque curve is steeper, which allows the rapid pick-up and reaction that rally drivers need. On the gravel stages of Sardinia, the quicker you can get the engine to react, the quicker you’ll be able to power out of the slippery corners. Quick-fire reactions are crucial, not only from the driver but the car too.

Such quickfire reactions, Neusser suggests, will find their way onto VW’s next generation of hot hatches. That’s a generation of hot hatches that Neusser all-but-confirmed will include a production version of the Golf R400, the 295kW four-wheel drive monster we saw in concept form last month. This is good news.

But Neusser is keen to stress that it’s not just VW’s hot hatches that will benefit from the firm’s rally knowledge. Even the lowliest supermini, he says, should be crisp and fizzy. “It must be fun to drive. My personal experience is that you can have a lot of fun with 100 kilowatts. When it’s precise…”

Amen. But the race’n’road relationship, Neusser stresses, isn’t a one-way street. The tech flows the other way too. The rally outfit has adopted VW’s road car testing philosophy, in which each part is individually lab-tested in a multitude of cruel and unusual ways.

“VW has a world of labs,” he says. “And you will find each component test you can ever think of. Shaker tested. Heat tested. Shaker AND heat tested.”

Only when each component passes those tests does it go into the mix for the next stage. The theory is that this creates a ‘pyramid effect’ of reliability: by the time the whole car is bolted together, nothing should fail.

And because each part is tested in isolation, says Neusser, “we can overstress it. If you put a component into a car, you can only stress it as much as the car as a whole can stress it. But in a single part test, you can subject it to more vibration. And then you get special robustness.”

And the proof that all this works lies in the dust of various rally stages: that tenth win on the bounce was a new WRC manufacturer record, which, when you consider the mighty machinery that have contested the series over the years, is a momentous achievement. Especially from a car that, deep down, shares at least a few strands of DNA with your nan’s diesel Polo…

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