General Motors has made it clear that it intends to focus most of its resources on just four core brands in North America but has left much doubt about the long-term viability of its other brands. The Buick, Chevrolet, Cadillac and GMC brands accounted for 83% of GM's total sales volume in the U.S. last year, leading to calls for the other brands, Pontiac, Saturn, Saab and Hummer, to either be axed or sold off.

The carmaker is now preparing a detailed plan showing how it will become viable, which it has to submit to the U.S. Department of the Treasury on February 17. GM has confirmed that it is looking for a buyer for its Hummer brand and that Saturn was also under review. Pontiac, meanwhile, is expected to be reduced to just a few models, while Saab could also be sold-off or axed altogether.

Inside sources, however, have revealed to Automotive News that GM executives have no solid plans for its non-core brands. The sources say finding potential buyers for any of the brands has been unsuccessful and that shutting down some brands was a very real possibility despite the risk of costly dealer lawsuits.

Some of the options reportedly being considered by GM include getting another company to run Saturn and absorb most of its dealers, convert Saab into an “autonomous” brand and moving production, engineering and marketing to Sweden – essentially cutting off all ties. Hummer, meanwhile, is still up for sale but will most likely be axed as no buyers have expressed interest in a while.

GM’s viability plans will eventually be examined by an auto industry ‘czar’ picked by President Barack Obama and if it is unacceptable the carmaker may be forced to repay the $13.4 billion in federal loans immediately.