The other front-runner for the loss-making manufacturer is understood to be US financier Ira Rennert and his Renco Group.
Fiat is also interested in Saab as part of its strategy to take over GM’s European units.
GM has made it clear that Saab must go by the end of the year and three suitors have been shortlisted, with a deal expected in weeks.
"According to sources close to GM the toughest battle is expected between US billionaire Ira Rennert and Swedish carmaker Koenigsegg," a Swedish newspaper reported.
It also said that Koenigsegg was lining up financing for the purchase among a group of “very wealthy people”.
Saab has said it has narrowed down a list of suitors to three and hopes to have a deal concluded in the coming weeks after its US parent, which is facing bankruptcy, said earlier this year it would cut loose the brand by year-end.