2010 Toyota Prius

2010 Prius

Toyota acknowledged Thursday that it found software design problems with the antilock brake system on the 2010 model year Prius. The company corrected the problem in Prius models sold since late January. The company said it was still investigating how to inform people who had bought the 2010 model prior to January. Toyota has sold approximately 100,000 units of the 2010 model since it went on sale in spring 2009.

The braking issue is not related to the unintended acceleration problem that recently led to a series of recalls on earlier Prius models, as well as eight non-hybrid Toyota models.

Paul Nolasco, a company spokesman, said the time lag for Prius brakes kicking in felt by drivers stem from the two systems in a gas-electric hybrid—the gas engine and the electric motor. When the car moves on a bumpy or slippery surface, a driver can feel a momentary pause in braking—lasting about one second—when the vehicle switches between the traditional hydraulic brakes and the electronically operated braking system. The brakes start to work if the driver keeps pushing the pedal.

While the Prius braking issue could cause safety problems at high speeds, the common complaint from drivers has been related to the “feel” or “sensation” during braking. A visitor to HybridCars.com wrote, “It feels like the car is sliding on ice but only lasts a second then the brakes hold again.” Others have described it as “lurching forward” or an “unsettling experience.”

Toyota said Thursday a software glitch is to blame for braking problems in the 2010 model. In late 2009, the National Highway Traffic Safety Administration started to track reports—so far about 100 consumer complaints—about the 2010 Toyota Prius’s braking performance.

Toyota has not yet issued a recall on the 2010 Prius. The likely fix would be a fairly routine software update. “We would want to be given a little time,” Hiro Yuki Yokoyama, Toyota’s managing officer, told reporters.

The Prius is Toyota’s third best-selling model in the United States.