Now is not the best time to be selling a General Motors car, especially if it is a Hummer, Pontiac, Saab, or Saturn. Through the bankruptcy process, it is expected that GM vehicle values will be diminished. However, loyalty-based incentives may offset some of the declined values, rewarding current customers for trading in a GM model for a new one. Once the “new” GM rises from restructuring, its used car values may increase slightly for those core brands it will retain: Buick, Cadillac, Chevrolet, and GMC.

In general, car values are all about supply and demand, though right now consumer confidence is playing a role, as well. In a random, nationwide Consumer Reports pulse survey, more than three-quarters (78 percent) of respondents said they were unlikely to consider buying a new car from an automaker in bankruptcy; 64 percent were very unlikely. We expect confidence will increase should a leaner, stronger GM emerge from bankruptcy. As seen with Chrysler, the uncertainty of what will happen proved a greater sales deterrent than the bankruptcy proceedings itself, and the same may prove true with GM. (Read: "Chrysler Group emerges from bankruptcy.")

Another key factor will be how dealers whose GM franchise license will not be renewed choose to proceed. Some may close shop, others will focus on other brands. However, many may convert into used car dealers, with a GM specialty. Such dealerships will be more welcoming of GM trade ins, plus be able to provide parts and service.

The rules for car buying and selling have become a bit more complicated with GM products, though the principles remain the same. Research the value for your vehicle if interested in selling or trading in, then compare those values against your local market, seeking multiple offers through new and used car dealerships. Don’t judge by classifieds listings, as those only indicate what people will accept for their vehicles, not what they actually sell for.

And don’t let your desire for a great deal on a new vehicle overshadow the need to get a fair deal on the trade in. Keep the transactions separate in your negotiations, and remember, you are driving the deal, not the other way around.

Read "What does the GM bankruptcy mean to you?" To get more answers to the most common questions and concerns about GM’s bankruptcy, visit our Auto Crisis hub.

—Jeff Bartlett