(February 3, 2010) Toyota , already grappling with recalls totaling 8.1 million vehicles on five continents, has been ordered by Japan's Ministry of Transportation to investigate a rash of consumer complaints about braking problems in its popular third-generation Prius hybrid vehicle.

The Japanese carmaker has received several complaints about braking in the Prius in both Japan and North America since the end of last year, Toyota spokeswoman Ririko Takeuchi said, according to the Automotive News.

The 2010 Prius gas-electric hybrid, which went on sale in Japan and the U.S. in May 2009, is not part of the recalls that extend to Europe and China, covering nearly 4.5 million vehicles.

The U.S. National Highway Traffic Safety Administration (NHTSA) has received about 100 complaints involving the Prius brakes. Two involved crashes resulting in injuries.

Japan's transport ministry said Wednesday it has received 14 complaints since July last year about brake problems with the Prius. The 14 complaints included an accident in July 2009, in which a Prius crashed head on into another car at an intersection. Transport ministry official Masaya Ota said two people were slightly injured in the accident.

A computerized search for the 2010 Prius on the online data base at NHTSA generated at least 102 complaints against the car.

The U.S. complaints accounted for at least two injuries. Drivers typically complain about losing braking ability — often while driving over bumpy roads — or feeling the brakes give way.

A report filed Feb. 1 reads: “While braking, if I hit potholes, the car speeds up from loss of braking action, even thou (sic) I am still pushing on the brake pedal.” Another complaint filed in September 2009 said the driver injured her neck when the brakes failed on her Prius and she collided with another vehicle.

Toyota is facing growing criticism that it has not done enough to ensure the safety of its vehicles. U.S. Transportation Secretary Ray LaHood told The Associated Press Tuesday that federal officials had to alert Toyota to the seriousness of the safety issues that eventually led to the recalls.

"They should have taken it seriously from the very beginning when we first started discussing it with them," he said. "Maybe they were a little safety deaf."

LaHood also said the U.S. government was considering civil penalties for Toyota for having dragged its feet on safety concerns.

In a separate issue with the Prius, the legendary co-founder of Apple, Steve “Woz” Wozniak, told technology magazine CNET.com that there is some sort of glitch with the electronics controlling the powertrain in his new Prius. It “goes wild” Wozniak says. He has reported his problems to Toyota and to NHTSA, but has never got a reply.

The original partner to Steve Jobs noted he has several Prius hybrids, but it is the newest, 2010 model that is acting up and, “This is software. It’s not a bad accelerator pedal. It’s very scary, but luckily for me I can hit the brakes.”

"Investors were worried the latest trouble involving the Prius could get bigger. The problem could pose a bigger question on Toyota's quality and safety," said Kazuhiro Takahashi, market analyst at Daiwa Securities SMBC Co. Ltd.