The first unitary car introduced by Rover in 1958 was a 3 liter saloon. The distinguished looking vehicle was very large in size and was designed by the famous stylist Davis Bache. The car with a luxurious interior had a 3 liter engine which had the ability to propel the car to an admiring speed of 100 mph. The original all drum set up of the car was replaced by the front wheel disc brakes in 1960.

The introduction of the Mk II which was a four door coupe with a comprehensive instrumentation and low roofline joined the saloon. Harry Weslake developed and redesigned the cylinder head later on which gave the car an increased acceleration and an improved engine power.

The year 1966 saw the Mark III version which had better seats and revised interior along with exterior trim. The major change was made in the following year when the Buick derived 3.5 liter V8 engine replaced the six cylinder engine of the car.

The PB5 was though not available in the saloon and coupe versions. It became a big hit with the government and was used to provide ministerial transport for some famous people which included the Prime Minister Harold Wilson. The production of the PB5 came to a halt in 1973.

The Rover P5 series was much larger than the P4 that it eventually replaced. The car had a 6F head engine and was also commonly referred to as the middle class Rolls Royce. It was also called the 3 Liter and 3 ½ Liter for the engine displacement.