The P4 was the first new Rover since the war, initially in a 6-cylinder version only – the '75'. The engine featured an aluminium cylinder head, two SU carburettors and a column gear change - fashionable in the export market.

The styling was inspired by the American Studebaker and manufactured by the Pressed Steel Company at Cowley. The car was the first Rover to have no noticeable running boards, though these did in fact still exist but were hidden by the doors.

The earliest cars had an unusual radiator grille with centre-mounted fog lamp from which it got the nickname 'Cyclops'. The models can be distinguished by the radiator grille; early models, such as this example, have fifteen bars.