Ford CEO Alan Mulally predicts that plug-in hybrids could be in showrooms in five to 10 years. Mulally made the comments during the announcement of a joint-effort between Ford and energy utility Southern California Edison to test twenty electric prototypes.

This is the first time that any timeline for the launch of plug-in hybrids has been made by a Ford executive, according to Reuters. When asked for a more specific date, Mulally only commented that he couldn’t go further than that, and that we should know a lot more within the next few years.

Ford will be contracting an as-yet unnamed battery company to develop the battery arrays for its new plug-ins, one of the major stumbling blocks for the roll-out of such vehicles. The key factor holding back the advancement of the green vehicles is the development of reliable and cost-effective lithium-ion batteries.

Pictured above is Ford's Airstream plug-in hybrid concept that was unveiled earlier this year at the Detroit Auto Show.