Formula One powerhouse McLaren secretly has begun work on a replacement for its legendary F1 supercar, while it also gears up to become a mainstream sports-car maker.

McLaren's Technology Center in Woking, England, has been building just 100 McLaren SLR supercars a year for Mercedes-Benz, but McLaren boss Ron Dennis reportedly has his sights set on producing 1,000 of its upcoming Ferrari F430-fighting P11s a year starting in 2011. The number, Dennis said, will rise to 4,000 cars by mid-decade as future models such as the Porsche 911-challenging P8 come on line.

At the top of those future models, according to McLaren Automotive Design director Frank Stephenson, will be an all-new version of the F1, the 240-mph exotic that rewrote the supercar rules when it arrived in 1992.

In an interview at the Geneva motor show, Stephenson said he is sketching ideas to replace the legendary Peter Stevens-styled F1. So, while spy photographers have been busy snapping pictures of P11 prototypes, Stephenson has moved on to the challenge of replacing one of the most revered cars in automotive history.

"For the F1 replacement, there are not the restrictions on us, like with P11," Stephenson said. "I am looking at a clean sheet of paper for the F1 replacement, and we are still trying to see what directions we want it to go in, in terms of its design.

"This one will be my influence from start to finish."Stephenson, who led design for BMW's first Mini, the original BMW X5, the reborn Fiat 500 and the Maserati MC12, said that McLaren has more road cars to come.

"The P11 is the building block for the whole of the McLaren automotive range," he said. "It's really a Ferrari F430 competitor, and there's plenty of room above that."

In spite of its glittering engineering reputation, though, McLaren's automotive division has yet to achieve a commercial success. The original F1 never sold in the numbers McLaren had hoped. Its last project, the Mercedes-Benz McLaren SLR, was equally stunning, but Mercedes has chosen to use its in-house AMG performance division to design and engineer replacements, including the 2011 gullwinged SLS.

With the P8, the P11 and the next F1, McLaren has a chance to change all of that.