Toyota plans to service approximately 650,000 of the more than 2 million Prius hybrids it has built to date, to correct a potential flaw in a cooling pump that could cause overheating. About 390,000 of the affected models are in the U.S.
While the company hasn't yet released details on what it calls a "service action," the number of vehicles suggests that the repair applies to the second-generation Prius. Those cars were built from models years 2004 through 2009.
Toyota says it's not being compelled to recall the vehicles, but will do so under a new initiative to be more proactive in keeping customers satisfied. Further details are likely to emerge over the next week or two.
Prius hybrids were among the many Toyota and Lexus models investigated for possible floor-mat interference with the acceleration pedal, leading to complaints of so-called "sudden acceleration". The first resopnse was a directive from the NHTSA urging owners to remove all floor mats from their Priuses (and other models).
2004 Toyota Prius accelerator pedal after being shortened as part of sudden-acceleration recall
The issue came to a head when a Lexus accelerator pedal apparently became trapped under a floormat, causing the car to speed at high rates in Southern California. That car ultimately crashed, rolled over, and burned, killing four people including the driver, a California Highway Patrol officer.
A National Highway Traffic Safety Administration investigation concluded that those accidents were largely due to driver error, but Toyota recalled second-generation Prius models (among others) to shorten the accelerator pedal so it could not catch on any carpets or floor mats.
Toyota also performed a separate service update earlier this year to improve driver perception of the braking system action, but on 2010 Prius models only. In that case, the brake pedal could feel as though it was not responding under certain interactions among the Prius regenerative braking system, friction brakes, and anti-lock brake control system.
Early this year, we published a complete guide to Prius recalls for braking and acceleration issues. Over the past two years, Toyota has recalled almost 9 million vehicles.
The company is expected to unveil a new six-seat "people carrier" or small minivan model of the Toyota Prius hybrid at January's 2011 Detroit Auto Show, to go on sale in March. It has teased the new version on Facebook, and photos have emerged from Japanese magazines.