If you own a GM car, life won't change too drastically. The government has already stepped in and said it would guarantee warranties from companies in bankruptcy during the restructuring period. And GM has said it will honor warranties if it goes into bankruptcy
If you own a Saturn, a Saab or a Hummer, car models that GM is trying to sell, the new owner will probably take over the warranties. The contract isn't usually changed according to Consumer Reports. But going forward there may be modifications to the warranties on these cars.
If you bought a dealer-specific warranty instead of a factory warranty for your GM car, your risk is bigger because dealers go out of business more easily. But experts say there's little chance that GM will liquidate.
If you're in the market for a car, a majority of GM models have great incentives and you don't have to worry about warranties. But make sure you buy a manufacturer-backed extended warranty from the automaker -- not the dealer's.