The Tech Center, which opened in 1956, is a National Historic Landmark. Its most recent major renovation was made in the design dome in December 2014.
The campus is the nerve center for GM's global vehicle development and is home to 19,000 engineers, designers, information technology workers and other employees. Many of GM's vehicles for North America and overseas are developed there.
GM has said that the center is in need of major upgrades to modernize its collection of dozens of '50s-era buildings, roads, tunnels and other infrastructure. More contemporary facilities could help the company better compete for talent with Silicon Valley and other more modern tech hubs.
A major storm last August flooded several buildings, causing roughly $100 million in damage and displacing thousands of workers for several days.
Reuss said not all needed flood repairs have been made, noting the design basement is still "pretty destroyed."
He said no area or building will be untouched by the renovations. All the needed updates became clear after the August flooding, he added.
Mike Colias contributed to this report.