Frank Weber, the German-born engineer in charge of the Chevrolet Volt, is moving back to Germany to take a senior management role at Opel.

He will be replaced by Doug Parks, who has been working at Opel since 2007 as chief engineer for GM's global compact cars, which include the Opel Astra and Chevrolet Cruze.

General Motors Co. spokesman Dave Roman said today that Weber's title has not been announced. Roman said Weber will help manage Opel product development once GM closes a deal to sell a controlling stake in Opel to Magna International Inc. and a Russian investor, Sberbank.

The move, Roman said, was planned. He said Weber's assignment in the United States is ending now that the Volt development is nearly complete and the car is ready for production.

“Coincidentally, the move timed pretty well for the development team. The Volt is now in execution mode,” Roman said. “Frank's done a great job leading the team.”

Weber, 43, led the powertrain and electronics engineers as they designed and tuned the Volt's gasoline-electric powertrain.

Unlike other hybrids, the Volt's gasoline engine does not drive the wheels. Only an electric motor does. On the Volt, the gasoline engine is connected to a generator that creates power for the electric motor after the car has traveled 40 miles on batteries.

Opel will have its own version of the Volt, called the Ampera, in late 2011, one year after the launch of the Chevy version of the hybrid.

Weber's move is GM's second significant departure from the Volt team in the past month. In September, Bob Kruse, executive director of vehicle engineering for hybrids, electric vehicles and batteries, left to start a consulting firm. GM immediately named GM engineering veteran Micky Bly to replace Kruse.