New Cadillacs like the hot ATS-V Coupe are starting to change Cadillac's image. New Cadillac chief Johan de Nysschen plans to accelerate those changes. Source: General Motors Co.

From a distance, Johan de Nysschen appeared to have a great job. The South African native, a longtime executive at Volkswagen's Audi brand, had been hired in 2012 to run Nissan's Infiniti luxury brand. Nissan has large expectations for Infiniti, in China and elsewhere, and the bold-minded de Nysschen seemed like the right man to lead it to the big time.

But in a surprise move, he left Nissan last year -- to take on a similar role for General Motors (NYSE:GM) as head of its Cadillac brand.

Why? Cadillac for years was known mostly for building cushy "rolling sofas" that sold to a dwindling audience of older Americans and almost nobody else. The brand had shown signs of life in the last decade, introducing some well-regarded rear-wheel-drive sedans and gaining a toehold in China's surging luxury market, but it was a long way from global glory -- and a very long way from being considered a peer of German brands like Audi.

Why would de Nysschen take on that long-shot task? In part, because he relished the challenge, of course. But he was also able to see the changes happening at General Motors, and the potential to do something dramatic with its tarnished old luxury brand.

We asked de Nysschen about his decision to join GM when we caught up with him in Detroit earlier this month. In this short video, shot on Cadillac's show stand at the North American International Auto Show, you can hear him explain why the job of running Cadillac intrigued him so much -- and why he thinks the brand has such great potential.