That’s because most trips are short. Vehicles driving less than 30 miles a day account for about 60 percent of annual U.S. passenger-vehicle miles, according to the U.S. Department of Transportation. Meanwhile, batteries are heavy. Michalek says that plug-in batteries, plus the structural material to support them, could substantially increase the weight of a car. “If you’re carrying around batteries that you’re not using, you’re spending more money and actually hurting the planet,” says Michalek.
Etienne Plas, a European spokesman for Toyota, says that three plug-in Priuses test-driven by employees of power-company Electricité de France since November 2007 are demonstrating a significant improvement in fuel efficiency. “In France, the early testing indicates that for trips up to 25 kilometers in duration, we see fuel efficiency up to 60 percent better than a regular Prius,” says Plas. “That’s quite significant.”
Plas says that Toyota is still studying how frequently test drivers plug their cars in–a variable that, as Michalek notes, will have a large impact on the plug-ins’ real fuel efficiency. But even consumers who never plug in are likely to see some benefit from the low-range Prius, at least when they’re driving in town. The Prius already captures energy from braking to recharge the battery. According to Plas, that energy can actually max out a small battery in stop-and-go driving. “With the current Prius, if you are in really heavy city traffic and you keep on braking, you will not be able to capture all the energy,” he says.
Such economic and environmental details could make the difference for automakers in the months and years ahead, as they seek to woo consumers back to showrooms. Auto sales in the United States in November were 37 percent lower than in 2007, according to industry tracking firm Autodata. Relatively pricey hybrids were hit even harder, slumping 53 percent relative to November 2007.
This spring, Toyota plans to shut down all of its Japanese production for 11 days to reduce the resulting supply glut; most automakers have taken similar steps. But Toyota remains convinced that high gas prices will be back to drive the continued electrification of the industry as a whole. As Irv Miller, vice president for environmental and public affairs at Toyota Motor Sales USA, said in Detroit this past weekend, “Last summer’s four-dollar-a-gallon gasoline was no anomaly. It was a brief glimpse of our future.”
Gain the insight you need on transportation at EmTech MIT.