A hands free driving aid that is legal in the UK is being investigated after cars in which it was being used were involved in two fatal crashes in the US.

Ford’s BlueCruise system was operational in two Ford Mustang Mach-E cars when the incidents occurred. The crashes are being investigated by safety regulators in the US, and Ford are working to support the investigation. However, there are obvious safety concerns with the BlueCruise system, which uses road markings, speed signs and evolving traffic conditions to control steering, acceleration, braking and lane positioning.

BlueCruise was approved for use on UK motorways by the Department for Transport (DfT) last year. It is classified as a Level 2 autonomous system, which means it can only be activated on 2,300 miles of pre-mapped motorways in England, Scotland and Wales, called Blue Zones. It is the only driver assistance technology currently permitted in the UK which allows the driver to take their hands off the steering wheel.

However, when using BlueCruise drivers must remain attentive at all times, and the system will be able to monitor how alert drivers are. If driver inattention is detected, the vehicle will issue a series of warning messages, alerts and brake activations, and if necessary slow the vehicle down.

BlueCruise was tested extensively by Ford engineers as part of the validation process for driver assistance systems. The DfT declined to comment on the US incidents, but said the system’s approval for use in the UK was issued following a rigorous examination and assessment process.