General Motors has finalised a deal to sell its Saab car business to tiny Swedish supercar-maker Koenigsegg in what is expected to be the first in a series of big sales.

The agreement comes after weeks of uncertainty about the degree of support for the bid from Koenigsegg’s backers, after a preliminary deal for the sale was struck in June.

Koenigsegg was previously little-known outside of luxury car circles, as it makes high-performance sports cars that can sell for £750,000 and employs only 45 staff. But questions remain regarding the financing of the deal. A statement by GM Europe was vague about terms beyond calling the deal a “stock purchase agreement”.

“This contract is an important step in the journey to a potential deal,” Carl-Peter Forster, head of GM Europe, said in the statement. “The closure of the deal is contingent on the funding commitment from the European Investment Bank, guaranteed by the Swedish government.”

GM, which emerged from bankruptcy protection on July 10, plans to sell its Saturn and Hummer brands and its European operations, centred on Opel.

The German government and GM played down hopes last week of a quick Opel sale but the former reiterated its support for a deal with Canadian bidder Magna. Saab managing director Jan Ake Jonsson called the deal a “milestone” but added that there were still some issues to be resolved. He said Saab’s reorganisation, which will be complete this month, had helped to create a better supply and demand balance through reduced inventories and restore the carmaker’s balance sheet. “So now is the time to exit the reorganisation,” he said.