As with previous versions the Mk III Rover 3-Litre was available as either a four door Saloon or four door Coupe. The Coupe retained its low roof profile and sold less than its Saloon counterpart.

The Rover P5 3 Litre range had established itself as one of the best selling British luxury cars of the Sixties. By 1967 the 3 Litre was beginning to show its age and a new powerplant was needed, enter one the famous British engines of all time, the Rover V8. The V8 engine was really a copy of a 1959 American Buick design, measured 3528cc and give the new model part of its name; the B in P5B stands for Buick.

The body of the new model, known as the P5B 3.5 Litre, remained similar to the old model although the sporty, Rostyle road wheels suggested extra performance. Power steering and automatic transmission were now standard equipment and the car continued to appeal to its loyal customer base. As before the Coupe model featured a lower roof line and thinner door and B-post pillars. Production of the P5B continued until 1973.