The Princess 3-litre was discontinued in June 1964, and replaced in 19 August by the Princess 4 Litre R. Visually, body changes includes the removal of the rear wing fins and the fitting of new horizontal rear light clusters, with a raised boot sill. Wrap-around integrated park lights and direction indicators are fitted on the front, and the fog lamps are now fitted within the horn apertures. The front and rear windscreens are set more upright to increase interior space, and as a result there is no overhang lip over the windscreens. Optional 'Selectaride' self-levelling suspension could be fitted. The brake circuit has an inertia pressure limiting device to reduce the risk of rear wheel lock-up. The Princess R is the first time Rolls Royce had ever supplied one of its engines to another car manufacturer. It is the outcome of the technical collaboration between Rolls Royce and BMC announced in January 1962. Both companies are pointing out that the BMC Princess R is not competing with Rolls Royce, but rather an attempt to combine the experience of both companies in one product. The Princess R replaces the outgoing Princess 3-litre MkII, but does not replace the present Vanden Plas 4-litre saloon & limousine, which continue with the existing specification, including the 3993cc Austin six-cylinder engine, and fitted to customers' individual requirements.
The Rolls Royce FB60 engine provides 175 bhp gross power at 4800 rpm, enough to propel the car on to a top speed of 112 mph. The gearing provides engine revs of 4300rpm at 100 mph, compared to the 4800rpm at 100 mph for the Princess MkII. The car is fitted with the Borg-Warner model 8 automatic gearbox. This is the big brother to the Type 35 commonly used in the old Princess.
Vanden Plas 1100 Saloon is a luxury variant of the popular front wheel drive 1100. It appeared in the autumn of 1963 powered by a twin-carburettor 55-bhp version of the 1098-cc engine unit. Features include a vertical-bar grille, luxury trim, full carpeting, a wooden facia and auxiliary lights. A sunshine roof is optionally available.