A vocal group of hybrid-vehicle enthusiasts says gasoline-electric vehicles could get dramatically better fuel economy if they had bigger battery packs that could be recharged by plugging them in at home.
According to Plug-In Partners, a group urging automakers to build the modified hybrids, the bigger battery packs would enable a hybrid such as a Toyota Prius or a Honda Civic to get as much as 80 mpg. The group, based in Austin, Texas, said 11,000 people have signed petitions calling on automakers to develop plug-in vehicles.
Plug-In Partners this year launched a promotional campaign backed by 252 municipalities, electric utilities and national policy groups.
Some automakers, such as Ford Motor Co. and Toyota Motor Corp., are looking into plug-in hybrids or PHEVs, but none are planned for production -- yet.
Engineers say the nickel-metal hydride batteries used in today's hybrids would weigh down a vehicle and make it less efficient when it is being driven by the gasoline engine.
"Certainly with the cost of carrying around a full electric powertrain and the cost of carrying around a fully capable EV battery, it is a very expensive proposition," says Tom Watson, Ford's manager of hybrid propulsion systems.
But lithium-ion batteries, expected to replace nickel-metal batteries by 2010, are lighter, smaller and more powerful and could make plug-ins practical, Watson says.
Automakers failed in the 1990s with pure electric vehicles such as the GM EV1 and Toyota RAV4 EV, mostly because of high costs and the limited driving range. A plug-in EV would not stop moving if the batteries ran out of juice because the gasoline engine would provide the power.
"Most market studies have shown that people like the idea of plugging in and refueling at home," said Mark Duvall, manager of technology development at the Electric Power Research Institute in Palo Alto, Calif.
Duvall says PHEVs could be profitable if automakers put them into high-volume production.
Ford spokesman Nick Twork said battery technology must improve and costs must come down before a plug-in hybrid could be put into production.
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