In response to past cases of unintented acceleration, the U.S. National Highway Traffic Safety Administration is proposing to standardize the propulsion-system shutdown timing of vehicles with a keyless ignition system. Under the proposed change to federal motor vehicle safety standard 114, engine shutdown would occur within 1.0 s of the vehicle operator pushing the start-stop button. The operator would have to push the button for a minimum of 500 ms to trigger shutdown. The proposed rule, drafted with input from SAE International, also calls for various alerts, such as when the operator attempts to exit the vehicle without first shutting down the propulsion system. The provisions would take effect Sept. 1, 2014, at the earliest, and perhaps not until Sept. 1 of a subsequent year, depending on when the final rule is published in the Federal Register. Comments on the proposal are due by March 12, 2012, and may be submitted electronically here. The docket number is NHTSA-2011-0174.