US auto safety regulators have opened an investigation into Tesla's Model Y SUV after getting two complaints that the steering wheels can come off while being driven. The National Highway Traffic Safety Administration says the probe covers an estimated 120,000 vehicles from the 2023 model year. The agency says in both cases the Model Ys were delivered to customers with a missing bolt that holds the wheel to the steering column. A friction fit held the steering wheels on, but they separated when force was exerted while the SUVs were being driven.