Image: Toyota Prius 2010
David Dewhurst  /  AP
The 2010 Toyota Prius. Some drivers have complained about experiencing problems with the auto's braking system.
Image: Paul A. Eisenstein, msnbc.com contributor
By
msnbc.com contributor
updated 12/29/2009 7:29:56 AM ET 2009-12-29T12:29:56

It took Bob Becker by surprise. As he approached an intersection on New York City's West End Avenue, not far from his home, he began to brake his 2010 Toyota Prius. But then the hybrid hit a pothole and suddenly, says Becker, it felt like the brakes weren’t working.

“It was a sensation of losing control,” said the 39-year-old human resources executive. It was all the more disconcerting as the light had changed and pedestrians were starting to cross the street. “The first time it happened on that corner it scared the hell out of me. I wasn’t sure I could stop in time.”

Becker was able to slam back down on the brake pedal just in time to avoid an accident. But in the weeks to come, the problem with his Prius repeated itself over and over, to the point he now has to prepare in advance when he’s coming up on an intersection, driving through traffic or exiting a freeway.

He’s not alone.

Chat rooms such as Priuschat.com dedicated to Toyota’s fuel-efficient hybrid are peppered with concerns raised by owners of the third-generation Prius, which was launched for the 2010 model year. At least 33 complaints alleging safety problems with the '10 Prius, most often involving braking issues have been filed with the National Highway Traffic Safety Administration’s Office of Defects Investigation.

NHTSA confirmed receiving complaints, which are a matter of public record, but would not comment further. A Toyota spokesman said no formal investigation is under way, but added that Internet traffic and other complaints had made the company aware of the concerns.

What happens next is uncertain. The government could launch a formal investigation and, if it were to find evidence of a safety defect, could work with the automaker to find a fix, which  might ultimately lead to a recall. Toyota could also take action on its own.

For now, though, owners have expressed frustration that their complaints are being ignored by Toyota dealers.

Becker said his dealer told him the problem was normal with anti-lock brake systems but he says, “I’ve never experienced anything like it” with other vehicles.

"Everyone is looking at antilock brakes but there are other systems that could be responsible for the behavior people are reporting. We just don't know," said Mike Michels, a spokesman for Toyota Motor Sales U.S.A.

There’s no easy way to determine what, if anything, is actually happening, but there’s no question that the brakes on the Prius are more complex than those on conventional automobiles.

Prius brakes are hybrids in their own right. When a motorist applies pressure to the brake pedal, the Prius brakes first go into regenerative mode, recapturing kinetic energy normally lost and turning it into electric current to recharge the vehicle’s batteries. For more aggressive stops, Prius uses a conventional, hydraulic braking system.

Several mechanics suggested it could be possible that the sensors controlling the regenerative braking system might malfunction when the wheels are jarred by a hard bump and briefly disengage, but an accurate determination has yet to be made.

A safety problem with the Prius could be particularly significant for Toyota. A year ago, the Japanese company seemed to be on top of the world, having topped General Motors for the first time to become the world’s best-selling automaker. Since then things haven’t gone very well.

Sales in the key U.S. market have tumbled sharply, a major reason why the company has gone deeply into the red. At the same time, Toyota’s coveted image as a maker of safe, reliable vehicles has taken a series of body blows.

The most significant came in October, when the automaker announced it would need to recall 3.8 million vehicles because floor mats could become tangled in their gas pedals, potentially leading to runaway acceleration. The announcement followed a widely reported incident in August, when an off-duty California Highway Patrol officer and three members of his family were killed in the fiery crash of a Lexus sedan that hit speeds of more than 100 mph after the gas pedal jammed.

There have been other problems, including the recall of 110,000 Tundra pickups that federal investigators found were prone to excessive corrosion that could lead to brake failure and even having spare tires snap off while driving. Meanwhile, NHTSA is investigating claims that 2006 Corolla and Matrix models might unexpectedly stall out, sometimes at highway speeds.

Trouble with Prius would be particularly problematic, according to analyst Stephanie Brinley of the consulting firm AutoPacific Inc., because of the hybrid’s high profile.

To help rebuild momentum, Toyota has been spending more than $1 billion in the current  quarter on an aggressive marketing campaign in which the Prius plays a disproportionate role considering its relatively modest sales.

If Prius wound up the target of a high-profile recall, or even just a formal safety investigation,  it could further damage the company's reputation.

A version of this story initially appeared on TheDetroitBureau.com, an independent Web site co-owned by Paul Eisenstein.

© 2013 msnbc.com.  Reprints

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