A few dozen Prius owners, eager for the benefits that plug-in hybrids offer and tired of waiting for auto manufacturers to produce them, have converted their hybrids into PHEVs, even though the modifications may void parts of the cars’ warranties. Felix Kramer of Redwood City, California, did it. So did Ryan Fulcher of Seattle, Todd Dore of Chicago, and Ron Gremban of Corte Madera, California, among others. Google’s RechargeIT.org site shows a map of vehicles that have been converted to PHEVs, and they are popping up all over the country.

These plug-in pioneers modified their cars for more than their own benefit. They did it to make a point: If they could make a plug-in hybrid, the major car companies could too—and should.

Kramer, Gremban, and a cadre of volunteers formed the California Cars Initiative (CalCars.org) and in 2004 converted Gremban’s Prius to a plug-in hybrid, doing the work in his garage. They added inexpensive lead-acid batteries and some innovative software to fool the car’s computerized controls into using more of the energy stored in the batteries instead of using the engine, dramatically increasing fuel efficiency. Several small companies like EnergyCS in Southern California and Hymotion in Canada have started doing small numbers of conversions for fleets and government agencies, using longer-lasting, more energy-dense lithium-ion batteries. 

Kramer hired EnergyCS to convert his Prius as a test case, and has reported on a typical day traveling 51 miles, mostly on the highway. At fuel efficiencies of 1 gallon of gasoline and 15.3 KWH of electricity expended to travel 124 miles (the equivalent of about two to four cents per mile for electricity, depending on local retail rates), his plug-in hybrid used 61% less gasoline and cut the vehicle’s greenhouse emissions in half. The total fuel cost? $1.76 instead of the $3.17 the car would have required on gasoline alone.

CalCars.org and the national Electric Auto Association have created an open-source “Wiki” Web site with instructions for do-it-yourselfers who want to convert their own hybrids to plug-ins. They hope to put together a video and eventually sell a package of components for individuals wanting to convert their hybrids. (See www.eaa-phev.org.)