The Detroit News and the Detroit Free Press report the 77-year-old died Saturday in Florida.

Brother Stempel served as a Foundation Trustee during SigEp's Campaign for the Heart in the 1990s.  He was a featured speaker/panelist at Conclaves in the 80s and 90s.  He graduated from Worcester Polytechnic Institute in 1955 and made his first gift to the Foundation in 1971.

Detroit-based GM says Stempel "admirably led the company during very difficult times in the early 1990s."

Stempel spent three decades at GM, including work as an engineer. The automaker credits him with leading the development of the catalytic converter, which it calls "one of the great environmental advancements in auto history."