The Austin-Healey 100 was the first car produced by the partnership between Austin and the Donald Healey Motor Company. The 100 was originally a one off car made by Healey, using the Austin A90 Atlantic as a base. The car made an impact on Leonard Lord, the head of Austin at the time, and an agreement was made to mass produce the car. The new model was named 100 due to the cars ability to reach 100mph, although it is also common to see it designated 100/4 due to the four cylinder engine. Two generations of the 100 were built: BN1 (1954-1955), and BN2 (1956). The most notable 100 variants were the race-derived 100S and the high performance 100M. These lightweight sportscars were commonly used as Race Cars. Production of the 100 ended in 1956, and it was replaced by the Austin-Healey 100-6.