German luxury sports car maker Porsche, racing ahead of a sluggish European auto industry, announced a 25 percent rise in net profits in the year to July 31.

Porsche AG's group net profit rose to 68.4 million marks ($46.01 million) in the year, up from 54.2 million marks ($36.45 million) from the previous year.The profit was well below what industry analysts expected, and Porsche shares tumbled 10 marks ($6.72) to 655 marks ($440) on the Frankfurt stock exchange.

Management board chairman Arno Bohn was pleased about current orders, which he said were up on last year's figures, but was cautious how long this could last.

Bohn hoped sales would remain roughly unchanged this year at about 3 billion marks ($2 billion).

And despite a weak U.S. car market, Porsche aims to retain its 25 percent market share of sports car sales in the United States.