The NHTSA said it is investigating Model X SUVs from 2022 and 2023 over concerns of seat belt failure.Contributor/VCG/Getty Images The NHTSA said it is investigating Model X SUVs from 2022 and 2023 over concerns of seat belt failure. The agency said it received two reports of seat belt failure. Earlier this month, the regulator began investigating reports of Model Y steering wheels falling off. The National Highway Traffic Safety Administration is investigating Tesla over concerns of seat belt failure.The safety regulator opened its investigation into Model X SUVs from 2022 and 2023 on Friday, according to a filing that was posted on the agency's website.