Car door handles seem innocuous. But in September, the National Highway Traffic Safety Administration launched an investigation into the Tesla 2021 Model Y’s door handles. More than 140 consumers have complained to the NHTSA about the door handles, according to a Bloomberg report published last month. The rules also appear to nix flush door handles by requiring automakers to build the handles with enough room for a hand to grip behind them. How pricey and complicated comes down to each automaker’s design.