In a move it says is aimed at speeding day-to-day decision-making, General Motors Co. announces a major management shakeup today that includes the retirement of five top-level managers and the promotion of several others to key positions.

Fritz Henderson, GM president and CEO, is replacing two senior leadership forums, the Automotive Strategy Board and Automotive Product Board, with one smaller executive committee.

Troy Clarke, 54, group vice president and president-GM North America; Gary Cowger, 62, group vice president-global manufacturing; Ralph Szygenda, 60, group vice president and chief information officer; Maureen Kempston Darkes, 60, group vice president, GM Latin America, Africa and Middle-East; and Michael Grimaldi, 57, GM vice president and CEO GM Daewoo all will retire before the end of the year.

Tim Lee, 58, currently GM North America vice president-manufacturing, will take over Cowger’s role as group vice president.

Terry Kline, 47, currently process information officer-product development, will be named vice president-information systems and services and chief information officer.