In a surprise move, the once heavily favoured consortium of Magna International Inc. and Sberbank changed its plans at the last minute and agreed that they would evenly split a stake in Opel, in a concession to critics, a source with knowledge of the matter told Reuters Newsagency.
"The final bids as well as GM's preliminary findings will then be reviewed with the German and other impacted governments, the EU Commission and the Opel/Vauxhall Trust Board," GM Europe said in a statement released after the deadline for submissions, without naming the bidders.
Berlin is expected to have a large say in the decision, since it would provide the bulk of up to 4.5 billion euros (US$6.4 billion) in expected loan guarantees for Opel.
Earlier, Magna and Brussels-based private equity firm RHJ International said they would submit final bids.
A source familiar with the matter told Reuters that China's Beijing Automotive also delivered a binding offer for Opel and its UK sister brand Vauxhall.
Magna and Russian partner Sberbank now aim to each take a 27.5 percent stake in Opel. Magna, a Canadian auto parts maker, originally planned to take just 20 per cent, with the Kremlin-backed lender holding the remaining 35 per cent.
The change could help soothe concerns in Germany over the potential influence of the Russian bank, which weeks ago began to talk about selling the possible stake holding in Opel to a domestic carmaker.
A stalemate between GM and Germany could be emerging over their differing preferences for the two competing bids, in which RHJ foresees shrinking Opel's production footprint to a more manageable level while Magna targets growth in the dynamic, but volatile, Russian market.
"Then (if there is disagreement between GM and Germany) we naturally have a problem and it becomes really complicated," said a source familiar with the thinking of Opel's trustees.
The trustees must formally approve any sale, and Germany and GM are evenly represented in the group.
Magna wants to convince the German federal and state governments that its plan best guarantees Opel its long-term independence from GM and ensures the European carmaker can decide for itself on issues including where it would develop new vehicle architectures or key modules and components.