WASHINGTON  Leading Democrats on the House Energy and Commerce Committee said Monday that Toyota relied on a flawed study in dismissing the notion that computer issues could be at fault for sticking accelerator pedals, and then made misleading statements about the repairs.

The comments, from Henry A. Waxman, chairman of the committee, and Bart Stupak, a subcommittee chairman, were made in an 11-page letter to James E. Lentz III, the president of Toyota Motor Sales U.S.A. The letter was released Monday on the eve of the committee’s hearing on the Toyota recalls, one of three scheduled.

Toyota earlier released more than 75,000 pages of documents, including 20,000 in Japanese, that the committee had requested.

The representatives, in a separate letter to the transportation secretary, Ray LaHood, said they also were concerned about the competency of investigations into Toyota’s problems by the National Highway Traffic Safety Administration, the federal safety agency.