Some lawmakers have expressed skepticism that faulty floor mats and defective accelerator pedals are behind Toyota’s unintended acceleration problems, and have accused the automaker of making misleading statements regarding its latest recalls.

According to The Washington Post, members of the House Energy and Commerce Committee – one of three congressional committees investigating the Toyota debacle – faulted the U.S. National Highway Traffic Safety Administration (NHTSA) for conducting “cursory and ineffective” investigations of Toyota defects.

Rather than floor mats and accelerator pedals, the lawmakers believe the unintended acceleration issue stems from a problem with the vehicles’ electronic throttle control system. In letters to James E. Lentz, President of Toyota Motor Sales U.S.A. and Department of Transportation Secretary Ray LaHood, Rep. Henry A. Waxman (D-Calif.), chairman of the committee, and Rep. Bart Stupak (D-Mich) assert thatin June 2004, the automaker and NHTSA officials discussed a chart showing that Toyota Camrys with new electronic throttles had 400 percent more complaints regarding “vehicle speed.” Among other things, the letters point out that approximately 70 percent of the sudden unintended acceleration events in Toyota’s customer database involved vehicles that are not subject to recalls.

The letter also claims that, based on a preliminary review of NHTSA documents, it appears that NHTSA lacks the expertise needed to evaluate defects in vehicle electronic controls, and its response to complaints of sudden unintended acceleration in Toyota vehicles appears to have been seriously deficient. Among other things, NHTSA officials told investigators that the agency doesn’t employ any electrical engineers or software engineers.

Since September, Toyota has recalled nearly 8 million vehicles worldwide for issues involving unintended acceleration. As we’ve reported previously, the NHTSA has now received more than 2,000 complaints of sudden, unintended acceleration with Toyota and Lexus vehicles that involve 34 deaths and hundreds of accidents since 2000. Toyota has blamed the problems on faulty floor mats and defective accelerator pedals.