GM has extended the deadline for Spyker to raise the funds needed to buy Saab.
GM had originally demanded that a deal be concluded by 12 o'clock today (Thursday) but has now extended that until 7 January.
"The December deadline has been lifted and the final offer from Victor Muller [chief executive of Spyker] must be made by 7 January now," said a spokesman for GM Europe.
Spyker had originally hoped to receive financial support from the European Investment Bank (EIB) for its attempt to buy Saab.
But with the EIB money not forthcoming, Spyker must raise funding in the Netherlands and in Russia.
Muller has said that if a deal is achieved, Saab and Spyker Cars would operate as sister companies, with Spyker benefitting from Saab's technical resources and its distribution network, and Spyker bringing its entrepreneurial skills to Saab.