(CNN) -- Toyota Motor Corp. has recently been in the hot seat after issuing massive recalls because of problems related to the accelerator pedal in several of its auto models.

To date, 8.1 million vehicles worldwide have been recalled by the manufacturer, with the possibility of more to come after Thursday's announcement by the National Highway Transportation Safety Administration of a formal investigation into brake problems with the 2010 Prius.

As the company's woes continue to mount, there has been some speculation from critics such as Rep. Henry Waxman, D-California, as to whether Toyota's recent problems with sudden unintended acceleration go beyond the problems already identified.

Speaking on Wednesday to CNN's Campbell Brown, Larry Webster of Popular Mechanics magazine spoke at length on the problem, saying that "in the last decade, there have been tens of thousands of reports of sudden unintended acceleration in cars made by all the manufacturers." Is this true?

The CNN Fact Check Desk wondered: Which other car manufacturers have had a problem with sudden unintended acceleration?

• Sudden unintended acceleration occurs when a car continues to move forward, often at increasing speeds, without the driver pressing on the accelerator pedal.

• While Toyota is basing its current recall on the possibility of floor mat entrapment and sticky accelerator pedals, many factors can contribute to the problem of sudden unintended acceleration in vehicles. Reports from the NHTSA have blamed it on many other factors, including frayed throttle cables and cracked cruise-control computers.

• The top five manufacturers of cars driven in the United States are General Motors, Toyota, Ford, Honda and Chrysler.

• The NHTSA's online database indicates that every one of these five has received numerous consumer complaints of sudden unintended acceleration in more than one of its models. Each manufacturer has faced a formal investigation into these complaints by the NHTSA and as a result has had to recall vehicles to fix various conditions that led to the problem.

• Recalls due to incidents of sudden unintended acceleration are not limited to the big five manufacturers. According to the NHTSA database, recalls have also been issued for vehicles made by Nissan, BMW, Volkswagen, Mitsubishi, Subaru, Mercedes-Benz, Kia, Mazda, Land Rover, Suzuki and Volvo.

• In December 2009, Consumer Reports published an article that said 41 percent of the sudden acceleration complaints received by the NHTSA in 2008 pertained to Toyota and its luxury brand, Lexus. Ford came in second behind Toyota with 28 percent of the complaints relating to U.S. models.

• Bottom Line: Sudden unintended acceleration is not a problem limited to Toyota. Many car manufacturers, including the other four with the largest shares of the U.S. market, have had to recall vehicles because of this issue.