Toyota Motor, Fiat Chrysler Automobiles, Volkswagen and Mitsubishi Motors are still selling new vehicles with defective air bags that will eventually need to be recalled, according to a report by a U.S. lawmaker overseeing the agency handling the largest-ever auto safety recall.

Automakers confirmed they are continuing to sell some vehicles with ammonium-nitrate inflators without a chemical drying agent, and cited engineering and supply challenges to explain why they are still relying on the faulty airbags.