The Williams FW40 was a Formula One racing car designed by Williams to compete in the 2017 Formula One season. The car was predominantly driven by Felipe Massa and Lance Stroll, who made his Formula One début with the team. The number '40' in the chassis name signified the 40th anniversary of the team. In addition, it was the last Formula One car that Massa drove in his career, as he announced his retirement for a second time in November. In Belgium, the car appeared in British motorcycle rider Guy Martin's series "Speed with Guy Martin".