Carl-Peter Forster, General Motors Europe president, was noncommittal when interviewed by Die Welt newspaper about the future of Opel/Vauxhall.
He said that Canadian supplier Magna International is likely to win the bid but that the division could also thrive under the ownership of its US parent.
Forster also added that the Magna deal is the more likely option since all conditions have been met, financing has been put in place, and the contracts have been negotiated.
On the other hand, he said that Opel can thrive under GM under the condition that GM will be able to "establish worldwide standards while at the same time allowing regional freedom to create cars that work in the given markets."
Magna and Belgian investor RHJ International have made rival bids for Opel, which GM wanted to sell because it could not afford to keeping funding the loss-making unit.
Last month, GM's new board asked executives to look at other options besides selling off the German-based subsidiary.
The Wall Street Journal recently reported that GM could contribute more than 1 billion euros of its own money to retain Opel, while governments in the U.K., Spain and Poland that are home to major manufacturing operations would finance another 1 billion.