Plug-in hybrids: Not ready for primetime.

NEW YORK - As car buyers search for more fuel-efficient alternatives, interest in plug-in hybrids is increasing. Ordinary hybrids, like the Toyota Prius, use power from the vehicle's gasoline engine to charge batteries that in turn power electric motors. When these hybrids were first introduced, people had a hard time understanding that they did not need to be plugged in to get needed electricity.