Cadillac president Johan de Nysschen presented the latest addition to the brand's high-performance V-Series, the 2016 CTS-V sedan, to the media last week in Detroit. Source: General Motors.

Why does General Motors' (NYSE:GM) Cadillac need a high-performance sub-brand?

It's an interesting question. For years, Cadillacs were thought of as "a couch on wheels," as the brand's marketing chief, Uwe Ellinghaus, put it in a conversation with us in Detroit last week.

But times have changed. German luxury giants BMW, Mercedes-Benz, and Audi have all shown that high-performance luxury cars can sell -- and sell quite well.

But the business cases for cars like BMW's M5 -- or Cadillac's CTS-V -- go beyond profitable sales. These are brand-builders, models that have a "halo effect" on the other cars in the automaker's lineup.

Cars like the CTS-V also get car enthusiasts excited, and car enthusiasts are often asked for their opinions on cars by friends and acquaintances. If a well-heeled enthusiast is singing the praises of the latest Cadillac, his BMW-driving friends might take notice -- and check out a Cadillac themselves.

We knew that much, but it turns out there's even more to the business thinking behind high-performance luxury cars. At last week's North American International Auto Show in Detroit, we spent a few minutes with Cadillac president Johan de Nysschen, who came to the show to introduce the all-new 2016 edition of Cadillac's hot CTS-V sedan. We asked him to explain why the high-performance V-Series models are important to his efforts to make Cadillac a global luxury powerhouse. Check out the video below, shot right on Cadillac's show stand, to see just what he told us.