DETROIT (AP) — Bob Lutz, a giant personality in the auto industry, is set to retire from his post at General Motors Corp. at the end of the year, the company said yesterday.

The 76-year-old GM product development chief and vice-chairman is credited with revamping the automaker's product line and shepherding its efforts to roll out the Chevrolet Volt electric car.

Lutz is well-known for his off-the-cuff remarks. Despite his support of the Volt, he once said his biggest worry is that the "global-climate-change mania" in Washington will be coupled with "perhaps ill-conceived ways to curb fuel use," during an automotive conference in 2007.

Lutz will be replaced by Thomas Stephens, who now is executive vice president of global powertrain and quality.

The company said in a statement that Stephens will take over the product development post and become a vice chairman April 1. Lutz will stay as a vice-chairman and senior adviser until the end of the year.

GM said it is integrating its powertrain functions into their respective global GM functions, so Stephens, 60, will still have responsibility for global quality and powertrain engineering, but powertrain manufacturing will report to Gary Cowger, GM's group vice president for global manufacturing and labor relations.

GM said the changes are part of its efforts to restructure and become more efficient.

Lutz once said he would remain at GM until the company's reputation improved.

"At some point I would like to retire, and I'm not going to go until this perceptual or reputational lag is gone," Lutz said in 2007. "And I don't intend to work till I'm 90."