The XPAG or 'X' series engines were used in nearly all Morris and Wolseley cars until 1956, including many thousands of Morris 10/4 Utility cars & vans made during WW2.

The XPAG is a good compromise. Its long stroke bottom end shares a great deal with engines dating from the 1920s and 1930s. The cylinder head design is virtually identical to the A and B series engines fitted to later BMC and British Leyland cars.

The XPAG shares many of the characteristics of engines from different manufacturers used in most cars up to the 1990s