The Arrows A9 was a Formula One car which the Arrows team used to compete in the 1986 Formula One season. It was powered by the massively-powerful BMW M12/13 turbocharged inline-four engine. Unlike the BMWs used by the Brabham and Benetton teams whose engines were maintained and updated regularly by BMW, the Arrows engines were maintained by Swiss engine guru Heini Mader and were rated as the least powerful of the BMW runners. At the Hungarian Grand Prix teammate Christian Danner raced the A9 but retired after 7 laps with rear suspension failure.