The race to buy Vauxhall/Opel appears to have narrowed to three potential buyers: Magna, RHJ International and Beijing Automotive Industry Corp (BAIC).
Final binding bids for Vauxhall and Opel must be submitted today (Monday), with GM and the German government then deciding the winning bid in due course.
Magna, which was originally named as the preferred bidder, is understood to be preparing an improved bid in the light of offers from its rivals.
However, this bid is reported to include a demand for rights to Vauxhall/Opel's intellectual property as Magna wants to sell Opel cars under its own brand and make changes to Opel designs, as well as using Opel technology for new models.
Industry analysts say this is highly unlikely to be agreed by GM as it has been suggested that Russia is eager to get its hands on Opel's cutting-edge technology and apply it to the Russian car market. Magna's bid is supported by Russian state bank Sberbank.
Magna has also given a commitment to building the new Vauxhall Astra at Ellesmere Port and continuing production of the Vivaro van at its Luton plant until at least 2013. "Both the Vauxhall plants in Ellesmere Port and Luton are vitally important to us and are integral to the Magna concept," said Magna. "We are in ongoing discussions with unions and the UK government. We are committed to the UK and the Vauxhall brand." Russian newspaper Kommersant has reported that Magna will withdraw from talks if its offer is not accepted, rather than be drawn into a further bidding war.