The Williams FW38 is a Formula One racing car designed by Williams to compete in the 2016 Formula One season. The car was driven by Felipe Massa and Valtteri Bottas. The FW38 used the Mercedes PU106C Hybrid power unit. During qualifying for the 2016 European Grand Prix, the FW38 set the highest ever recorded speed of a Formula One car during an official session, at 378 km/h (235 mph). During the 2016 Mexican Grand Prix, the FW38 set the second highest ever recorded speed of a Formula One car during a race, at 372.5 km/h (231.5 mph).