Group Lotus CEO Mike Kimberley says he will retire from the U.K.-based specialty car company due to ongoing health problems.

An executive committee comprised of current board members, supported by Malaysian-based owner Proton Holdings Bhd, will assume day-to-day management of the auto maker until a permanent replacement is named.

Kimberley, who will turn 71 next month, underwent back surgery in late 2008, but says the procedure was only partially successful and doctors have advised him to retire in order not to jeopardize his long-term health.

“Sadly, it is on doctor’s orders that I am stepping down, but I will leave confident that Lotus is in great shape with a strong management team fully supported by our shareholder in Malaysia,” he says.

Lotus recently launched its all-new Evora model under Kimberley’s direction. Expected to be priced at about $70,000, the rear-drive, 2+2 Evora is underpinned by a Lotus-developed aluminum chassis and powered by a Toyota Motor Corp. 3.5L 276-hp V-6.

The Evora platform is expected to spawn a whole new range of cars for Lotus.

Kimberley is in his second stint at Lotus, having returned to the company in August 2005 as a member of the board. He was appointed acting CEO in May 2006 and named the permanent CEO the following September.

Kimberley originally joined the auto maker in 1969, ultimately being named CEO in 1982 before leaving in 1992 to oversee Southeast Asian operations for General Motors Corp., which owned the British car maker at the time.