I think that GM had some nifty technology but it was too expensive. They saw that they would be forced to keep building these cars and selling (leasing) them at a loss while they drew sales away form profitable car lines and cast the rest of their business in a bad light.
Ironically, GM is being punished for their short term mentality. Punished not by the government or consumer activists but by the market. Huge, fuel-guzzling vehicles have a large profit margin, until the day comes when they start sucking the wells dry. GM walked away from electric technology which could have formed the basis for successful, cost effective hybrid vehicles. Instead, GM spent money redesigning their huge, truck-frame SUVs which rolled out just in time for $78 oil.
For the record, I don't think pure battery powered road cars are economically viable with any foreseeable technology. The high price and operational limitations can not be overcome in the near future. Hybrids OTOH, are economically viable now (barely) and give up little in utility.