WASHINGTON, D.C. — The National Highway Traffic Safety Administration announced a new formal investigation into Toyota vehicles on Thursday.

This latest review from the NHTSA comes as complaints over the braking system on the 2010 Toyota Prius Hybrid model continue to grow in the U.S.

The NHTSA said it is looking into allegations of momentary loss of braking capability while traveling over an uneven road surface, pothole or bump.

The Office of Defects Investigation has received 124 reports from consumers, including four reports alleging that crashes occurred. Investigators have spoken with consumers and conducted pre-investigatory field work, NHTSA officials said.

"Safety is our top priority," explained Secretary Ray LaHood on Thursday. "That is why in recent weeks NHTSA has also issued a consumer advisory on the recall of several models of Toyota vehicles and the Pontiac Vibe involving pedal entrapment and sticky accelerator pedals. We will continue to monitor these issues closely."

Apparently, LaHood spoke with Akio Toyoda, Toyota president, late Wednesday. Toyoda reassured LaHood that Toyota takes U.S. safety concerns seriously and puts safety at the top of the company's priorities.

In response to the new investigation, the automaker issued a statement.

"Toyota is aware of NHTSA's intention to begin a preliminary evaluation centered on owner complaints of a braking issue with the 2010 model year Prius. Toyota will cooperate fully with NHTSA's investigation," the company stated.

Later in the day on Thursday, Toyota released more, saying "Some customers have complained of inconsistent brake-feel during slow and steady application of brakes on rough or slick road surfaces when the anti-lock brake system is activated in an effort to maintain tire traction," the company said.

"The system, in normal operation, engages and disengages rapidly (many times per second) as the control system senses and reacts to tire slippage. A running production change was introduced last month, improving the ABS system's response time, as well as the system's overall sensitivity to tire slippage. This preliminary evaluation addresses owner complaints specific to the 2010 Prius," according to Toyota.

Officials went on to say that the production change is not related to either the floor mat entrapment recall or the sticky pedal recall.

"Toyota will continue to evaluate the condition as it relates to owner complaints and will keep NHTSA informed of its progress," the company added.

According to the NHTSA, of the 100 investigations it opens every year, there are currently 40 open defect investigations. Three of these are related to Toyota.

Discussing the broad recall of eight Toyota models on Wednesday, LaHood said, "I want to encourage owners of any recalled Toyota models to contact their local dealer and get their vehicles fixed as soon as possible. NHTSA will continue to hold Toyota's feet to the fire to make sure that they are doing everything they have promised to make their vehicles safe. We will continue to investigate all possible causes of these safety issues."

According to a report via Dow Jones, NHTSA has begun a "fresh look" at Toyota's electronic throttle control systems and what impact electromagnetic interference on these systems could be.

The NHTSA told Dow Jones that it has no reason currently to believe there are safety defects in the systems or that electromagnetic interference could cause problems.

Instead, it is "a background examination of the underlying technological issues," NHTSA told Dow Jones.

Apparently, U.S. Transportation Department officials are also considering levying civil penalties against Toyota for the way it has managed the accelerator situation.

Repairs Begin for Acceleration Recall

This morning, the automaker announced that Toyota dealers nationwide have received the parts, information and training to fix accelerator pedals and repairs on the models involved in the accelerator issue. Repairs have begun. The actual repair requires about 30 minutes of work, officials noted.

The company also announced that it has begun mailing letters to owners of recalled vehicles to let them know when to bring their vehicles into a dealership. Owners will only receive a letter if their vehicle is involved in the recall.

"Nothing is more important to us than the safety and reliability of the vehicles our customers drive, and we are determined to live up to the high standards people have come to expect from Toyota over the past 50 years," said Jim Lentz, president and chief operating officer. "Everyone at Toyota is focused on making this recall simple and trouble-free for our customers."

"We're working hard to ensure that our dealers have the resources and support they need to make sure our customers get their cars fixed quickly," Lentz added. "The parts have been shipped, the dealers are trained, and they are already making the repairs. Many of our dealers are working extended hours — some 24/7 — and adding service technicians and other staff to complete the recall campaign as conveniently as possible. I appreciate the efforts that our dealers are making to take care of Toyota owners."

Furthermore, Toyota said its dealers throughout the country are taking extra steps to support customers during this recall.

Many Toyota dealers will offer extended service hours, and some are planning to stay open 24 hours a day until all customer vehicles have been fixed.

Others are adding greeters to their service drives, dedicating body shop capacity to expedite repairs, providing free car washes and oil changes, increasing owner communication and providing complimentary maintenance service, among other customer-focused activities.

To support these efforts, Toyota is sending checks of between $7,500 and $75,000 to its dealers in acknowledgement of the additional costs they are assuming to make it easier for customers to have the necessary repairs done quickly and conveniently.