LOS ANGELES (Bloomberg) -- U.S. government incentives to spur a market for battery-powered autos aren't a cost-effective way to cut oil use and tailpipe emissions compared with boosting sales of hybrids and plug-in cars that go short distances on electricity, a study said.
Battery breakthroughs, more-expensive oil and a more-efficient electric power grid will be needed to justify the expense, weight, and assembly-related costs of "large battery pack" cars, according to the review by Carnegie Mellon University, Arizona State University and Rand Corp., published this week in Proceedings of the National Academy of Sciences.
Hybrids similar to Toyota Motor Corp.'s Prius and plug-in hybrids that go about 10 miles on battery power offer fuel-use and carbon-exhaust savings similar to more advanced rechargeable models such as Nissan Motor Co.'s electric Leaf and General Motors Co.'s Volt, and at lower cost, the study found.
"It's not that large battery packs are bad, it's that they are not providing as many benefits per dollar," Jeremy Michalek, an engineering professor at Carnegie Mellon University in Pittsburgh who led the review, said in an interview. "Ordinary hybrids increase fuel economy substantially, and the incremental cost of those systems is getting relatively small." The study did not recommend specific models.
Congress in 2009 approved tax credits of as much as $7,500 for consumers to buy vehicles powered mainly by electricity to help cut emissions tied to global warming and oil imports, along with low-cost federal loans for carmakers to add or upgrade factories to build them.
Nissan, GM and startups Tesla Motors Inc. and Fisker Automotive Inc. have received loans they're using to build rechargeable vehicles. Nissan's Leaf hatchback, which goes about 70 miles per charge of its lithium-ion battery pack, costs $35,200 before the credit, and GM's Volt that goes about 35 miles per charge has a $39,145 starting price without the incentive.
Prius, averaging 50 miles per gallon of gasoline, doesn't qualify for a federal tax credit. Tesla's electric Roadster sports car costs more than $100,000 even with the credit and can travel more than 200 miles per charge. Fisker's Karma plug-in model that's being delivered to U.S. customers costs more than $80,000.
Toyota, the world's largest seller of hybrid autos, said this month the plug-in version of Prius that goes on sale early next year will travel 15 miles on electricity before the gasoline engine kicks in, when it averages 49 mpg. The car has a $32,000 base price, prior to a $2,500 federal tax credit, the company said.
"Current subsidies to support plug-in vehicle adoption favor large battery packs," the report said. Such packs "are expensive and heavy" and "are underutilized when the battery capacity is larger than needed for a typical trip," it said.
Both Toyota and Ford Motor Co., which are working together to develop a hybrid system for light trucks, provide funding for engineering research at Carnegie Mellon University, Michalek said. Neither company was involved in the report released today, which was funded by the National Science Foundation, he said.