Complaints to U.S. regulators of unintended acceleration in Toyota Motor Corp vehicles are down sharply as separate government and expert reviews of the matter move forward.

National Highway Traffic Safety Administration documents made available to a National Academies of Science panel examining vehicle electronics as a possible cause of unwanted acceleration industrywide illustrate volatile complaint trends for Toyota and other automakers.

The quality of Toyota's cars -- once a benchmark for the industry -- has come under scrutiny after the world's top automaker recalled more than 10 million vehicles globally since late last year, mostly for problems of unintended acceleration.

Reduced complaints for Toyota this summer, which regulators believe is partly due to ebbing publicity, do not alone substantiate the automaker's contention that its electronic systems are sound. But the drop could be an indicator that fixes for more than 8 million recalled vehicles worldwide for mechanical and equipment problems linked to unwanted acceleration are working.

We do feel our remedies have been effective, spokeswoman Cindy Knight said.

Regulators, who review each complaint, say complaints generally fall off when publicity eases even though Toyota has recalled thousands of other vehicles this year for other problems -- including braking on its signature Prius hybrid.

The unintended acceleration recalls in October 2009 and in January at the core of Toyota's safety crisis involved floor mats that could jam the accelerator pedal and pedals that did not spring back as designed.

Since 2000, electronic throttle control was cited in complaints associated with 52 Toyota crashes that reportedly killed 62 people, according to NHTSA's most recent figures. Regulators are reviewing complaints alleging 31 additional deaths unrelated to electronic throttle complaints.

Toyota is due to file an update soon with NHTSA on vehicles serviced under the big recalls, which regulators analyze to see if remedies are successful. The floor mat and sticky pedal recalls required design changes or replacement products.

Toyota has so far made repairs and other fixes on 1.7 million vehicles, or 78 percent of the recalled number, for sticky pedals, and nearly 40 percent, or 2 million, of models recalled for loose floor mats, it said. Certain Tundra pickups and Avalon and Camry sedans had both problems.


NHTSA received 9,600 acceleration complaints in the past 10 years and Toyota represented about third, figures show.

Reports of alleged incidents to NHTSA about unwanted acceleration in Toyota and Lexus vehicles for 2010 have so far reached 1,500, most between January and March. February covered two-thirds of the total when publicity, congressional investigations and lawsuits hit fever pitch. There have been 400 related complaints against other automakers.

There were an estimated 100 Toyota-related acceleration complaints from April to June. The trend was heaviest in early spring. In June, complaints fell to zero or very low single digits for key models, like Camry, Prius, and Lexus, according to a review of the most-recent figures compiled by NHTSA.

At least two injuries were alleged. The 2007 Camry has accounted for more than 270 complaints overall, but only two last month. Complaints for other vehicles, including Corollas, Tacoma trucks, the hybrid Prius and Lexus models, were scattered for June. A few complaints have been noted in July.

Toyota, which maintains a complaint database, said it has also seen a drop in acceleration reports. Its investigation of 2,000 related complaints has turned up no potential cause beyond floor mats, faulty pedals and possible driver error, Toyota said this week. It is also testing its software-driven electronics for any glitches but says they are sound.


Other figures provided to NAS and separate documents reviewed by Reuters also reveal complaints industrywide for all problems have topped the 38,000 reports received last year.

NHTSA is facilitating more recalls. The turnaround was driven by criticism from safety advocates and some in Congress that NHTSA was too easy on Toyota previously.

So far, more than 300 recalls through June covered more than 10 million vehicles, according to NHTSA figures. All carmakers have had at least one recall. In 2009, there were 492 recalls covering 16.4 million vehicles.

Toyota shares were decimated by recall problems. Its U.S. price stood at $71.28 on Friday, about $20 below its 2010 high in early January.

Jeremy Anwyl, chief executive of buyer resource, said it is reasonable to expect a drop in complaints as publicity eases and recalled vehicles get fixed.

He said Toyota has loyal customers and can recover sales quickly enough. But a challenge remains attracting buyers that are on the fence over the jolt to the automaker's reputation for reliability and safety. That armor has a crack in it. That's the part that is hard to rebuild, Anwyl said.

NHTSA has begun a new review of unintended acceleration with the U.S. space agency, NASA. The NAS review is being conducted separately and is in its early stages.

Toyota faces lawsuits alleging unintended acceleration. NHTSA fined the automaker $16.4 million this year for failing to notify it in a timely manner of flawed gas pedals in recalled models.

(Additional reporting by Detroit newsroom, editing by Matthew Lewis)