Daimler has no firm plans now to produce a plug-in passenger car, but that could change. "I am convinced we can commercialize this technology," says Ferdinand Panik, an alternative-vehicle expert and retired Daimler senior official who now consults for various organizations, including EPRI. "First for the delivery van, and then for passenger cars as well." The plug, he and other proponents believe, has the potential to transform the burgeoning hybrid-electric vehicle market, in which Japanese automakers, led by Toyota and the surprisingly successful Prius, have established an early and commanding lead over their U.S. and European counterparts.

Cars that both plug in and fuel up? How about a switch on your dashboard that turns your car into an electric vehicle? For plug-in technology to succeed in passenger cars, one of the tricks will be finding a way to avoid befuddling a general public conditioned to do little more than turn a key, step on an accelerator, and buy copious quantities of gasoline.

Source: Hybrid Electric Vehicle Working Group

Annual Gas: Annual gas Consumption for vehicles driven an average of 59 km a day

As one U.S. driver told EPRI pollsters: "I'm lazy. I wouldn't be organized enough to remember to plug in."

For those who could remember to plug in, however, the benefits would be considerable. Like most people, you probably travel a set distance to and from work five days a week, and also make intermittent excursions of varied lengths. If you had a plug-in hybrid with a battery big enough to cover your daily commute, you would have, in effect, a pure-electric vehicle five days a week, but one that could burn gasoline whenever you wanted to go on a ski trip, visit your cousin, or drop off the kids at summer camp. You'd go to a gas station maybe six times a year instead of six times a month.

There would be other benefits, too. For example, that dashboard switch—the one that lets the driver put the vehicle into a pure-electric mode—could let the car operate in a crowded, downtown urban area where combustion-engine fumes and noise were unwelcome. And utility executives become visibly excited about the possibility of recharging millions of vehicle batteries at night, when their generating plants would otherwise languish. "Powering up generating plants in the day and then powering them down at night is very inefficient," notes Ed Kjaer, director of electric transportation at Rosemead-based Southern California Edison.

The first glimmerings of that vision are to be seen at Daimler's Kompetenz-center fur Emissionfrei Nutzfahrzeuge, known as KEN, where the plug-in hybrid project is based. KEN already does a modest but steady business converting small trucks, mostly Sprinter vans, to run on compressed or liquefied natural gas, electricity, or hybrid electric drive trains. The group has 7700 square meters tucked away in a cavernous Daimler truck engine factory in Mannheim.

On a rainy October afternoon, a couple of dozen Sprinter vans are scattered around the facility in various stages of conversion, many of them up on lifts. A pair in one corner, one orange and one white, are being outfitted with pure-electric drive trains; a tangled rainbow of harness wires spills out through their open front hoods. One of these Sprinters is destined for the University of Bremen in Germany and the other for Helgoland, a North Sea fishing and resort island where internal combustion engine vehicles are banned.