The Ferrari 643 was a car built by Scuderia Ferrari for the 1991 Formula One season. It was the successor to the Ferrari 642 and was used for the remainder of the 1991 season. The 643 was a redesign of the predecessor Ferrari 642. Towards the end of the season, Alain Prost was sacked for the second time in his Formula One career by a works team. He fell out with the team due to the lack of success throughout the season, and eventually said that "a truck would be easier to drive than this car". He was replaced by Gianni Morbidelli for the final round of the season.