The big Porsche Cayenne SUV accounted for about half of Porsche's sales last year. The new, smaller Macan SUV, shown here, should boost Porsche's -- and Volkswagen's -- profits again in 2014.

For the last few years, Volkswagen has been one of the most profitable automakers in the world, rivaled only by super-efficient Japanese giant Toyota.

What's the German company's secret? There are actually several, but a big one is the amazing profitability of VW's stable of luxury brands. As Motley Fool senior auto analyst John Rosevear explains in this video, Porsche in particular stands out for its tremendous profitability -- with a 2013 profit that nearly exceeded that of the much larger-selling VW brand itself.

http://www.youtube.com/watch?feature...&v=J3lyoOTkfJM

VW owns a bunch of luxury vehicle brands, including Audi, Bentley Motors, Lamborghini, and Bugatti, but the one that really produced some eye-popping results last year is Porsche. Last year the VW Group sold 9.7 million vehicles around the world, from tiny cars to big trucks. Porsche accounted for a little over 162,000 of those, just 1.7%. But Porsche accounted for 22% of the VW Group's total profits.

Porsche made almost as much money as the Volkswagen brand did, and the VW brand sold almost 6 million vehicles.