General Motors' sale of Sweden-based Saab is on track, although one of the key investors seems to be pulling out.

American car giant General Motors is on track with its plans to sell its luxury brand Saab Automobile to Swedish sports car maker Koenigsegg Group, representatives at Saab and Koenigsegg said to the Dow Jones news bureau on Monday.

"Everything's proceeding, we're still looking to be done by the end of the third quarter," Saab's spokeswoman Gunilla Gustavs said.

There’s been rowdy speculations that one of the key players of the Koenigsegg Group, American investor Mark Bishop, is leaving the constellation because of the massive attention the acquisition has brought about, adding further confusion to the already notable deal.

Saab is currently under creditor protection. The reorganisation will be allowed to continue until August 20 and the working process to get the Saab deal finished is in an extremely intensive stage.

Neither Saab nor Koenigsegg are willing to comment on the buyer's structure. Still, they said that the process is proceeding according plan.

"The only thing we can say is that we're still in the final negotiations," said Halldora von Koenigsegg, wife of Christian von Koenigsegg, the founder of the boutique sports car maker Koenigsegg Automotive, to Dow Jones. "We're aiming to get [the final agreement with GM] done as soon as possible. The negotiations are going well".

Also IF Metall, the biggest union at Saab, is confident that the deal will be fulfilled.

"For us the important thing is that we feel comfortable the buyer is a group that has the financial muscle [to lead saab in the future] - and we are feeling comfortable," said Paul Åkerlund, the union’s representatives.