Subaru chairman and chief executive officer Takao Saito will assume the position of president from Muller, who served as the top American executive for the past seven years.

Muller said his decision to leave has nothing to do with Subaru parent Fuji Heavy Industries Ltd's agreement last December to sell a 20 per cent stake to General Motors Corp, the world's largest automaker.

"I have an opportunity to do something that I've thought about for a while. It's a little more on the entrepreneurial side in the private investment business," Muller told Reuters.

Sales for Subaru of America, which offers the Impreza sedan, Legacy and Legacy Outback wagons and the Forester sport utility vehicle, were up 18 per cent for the first five months of this year over last year's comparable period.

Fred Adcock, promoted to executive VP of sales from senior vice-president, said sales are expected to climb 6 to 7 per cent this year to about 162,000 units (153,000). Saito said Subaru and GM have formed committees to study ways the two companies can benefit from the alliance, and talks will intensify later this month.