GM looks to be dipping its toes back into EV1 territory, with Reuters reporting that the still-number-one automaker is set to unveil a prototype plug-in hybrid vehicle at the North American International Auto Show in Detroit this January.

For its part, however, GM is keeping any details on the vehicle under wraps, no doubt content to let the inevitable hype machine run its natural course. The mystery ride would be the first plug-in hybrid electric vehicle (PHEV) from a major auto manufacturer, filling in the middle ground between the infamously-defunct all-electric car and the current enviro-friendly vehicles of choice: hybrids. Unlike a Prius or other hybrid, a PHEV can recharge its batteries from a regular household outlet — yet unlike the EV1, it can fall back on a diesel or gasoline engine when the batts run dry. Those looking for fix in the shorter term, however, can of course already upgrade their hybrid to the plug-in variety, albeit for a hefty price.