Codenamed `P5B.` the 'B' standing for Buick engine. This was the first Rover to take the famous GM 3.5 V8 engine which was to power the P6B, Range Rover and SD1 cars.
The V8 replaced the inline Rover 3 litre engine which powered the older saloon versions (and dated back to the P4). The 3 litre saloons were popular Prime Ministerial cars from Harold Wilson to Margaret Thatcher.
Rover revised its 3-Litre P5 range once again in 1965 with the introduction of the Mk III model. The Mk III now had a more powerful 134bhp version of the same 3-Litre engine used in the previous Mk I and Mk II cars. The Mk III now had a less fussy front grille and a full length chrome side moulding to distinguish it. The interior now had reclining front seats which were extremely comfortable. The rear seats were trimmed to match those in the front and were "individual" in appearance.
As before the Mk III Rover 3-Litre was available as either a four door Saloon or four door Coupe. The Coupe retained its elegant low roof profile and sold in smaller numbers than its Saloon counterpart
