The Jaguar Mark 1 was introduced in 1955. A series of midsize luxury sedans, the Mark 1 was Jaguar's entry into the midsize category, as its other models at the time were at the higher end of the autmotive market. The Mark 1 was the first Jaguar built using unibody construction, and was available with a 2.4L or 3.4L inline six engine. The Mark 1 was in production until 1959, when it was replaced by the Jaguar Mark 2.