Porsche – small, specialist purveyor of fabulous sports cars – is gobbling up a majority chunk of Europe’s biggest car maker, Volkswagen.

Porsche’s £7 billion spending spree will increase its share from 31% to more than half.

In effect, the Stuttgart specialist is taking control of a company 14 times its size.

This much we knew, but there’s one question on everyone’s lips: why?

CAR was granted a rare interview with Dr Wolfgang Porsche, grandson of the company’s eponymous founder and reclusive chairman of the supervisory board, to separate truth from tittle-tattle.

“I don’t see it as a gamble – I see it as a way of keeping our business stable,” he reflects.

“With volumes of only 100,000 cars a year, Porsche is too small to do everything itself. We need a big partner.”

He admits that Porsche’s association with Volkswagen will help it meet tough new CO2 rules from Brussels, as millions of smaller Polos and Golfs balance out the emissions of 911s and Cayennes.

It’s surely the biggest driver of the deal.

But Dr Porsche points out that the two companies can also share expensive R&D bills to bring down the cost of safety systems, hybrid engines and – get this – diesel engines.

On a Porsche! Don’t rule it out.

What did he learn from his father Ferry Porsche, we ask.

“To be cautious,” he says in a measured fashion.

“That success comes gradually. Our cars have progressed gradually.

We don’t do revolutions. We are not led by fashion. We are not trendy.”

Very Germanic. Very logical. But it could be the best £7 billion the sports car maker has ever invested.

For a full version of the interview with Wolfgang Porsche, buy the new June 2008 edition of CAR Magazine, celebrating Porsche’s 60th anniversary.