The Silent Sports Car in its 3 ½ Litre form had been a great success and a terrific opening chapter in the new era of the Bentley name and brand, now in the ownership and under the stewardship of Rolls-Royce. Following three years of production further improvements were unveiled in 1936 with the introduction of the 4 ¼ Litre model.
It was an evolution of the 3 ½ Litre model, retaining much of its predecessor's charm while improving upon its power and performance. The Bentley 4 ¼ Litre was essentially an upgrade to the 3 ½ Litre, fitted with a more powerful engine to suit Bentley’s sporty image. The demand for higher performance led to its introduction, catering to Bentley's clientele who desired a combination of both luxury and performance.
The Bentley 4 ¼ Litre was equipped with the same configuration inline six-cylinder engine which was a pushrod overhead-valve unit, still based on the Rolls-Royce 20/25 engine design, but enlarged for better performance. The engine displacement was 4,257 cc providing more power than its predecessor. While exact horsepower figures were not officially disclosed by Rolls-Royce (a common practice at the time), the 4 ¼ Litre was known to produce around 125 bhp, making it capable of reaching top speeds of around 80mph, depending on the body style and weight of the car.
The new 4 ¼ Litre motor cars whilst more powerful than their predecessor did share many other common technical features and attributes, with the basic chassis, braking system, suspension and gearbox all effectively identical. However, one major improvement was made to the clutch, which was considerably more robust and hard wearing than the 3 ½ Litre, which some might describe as delicate.
Steady development continued throughout the cars production and in late 1938 even more power was obtained when the overdrive models were introduced, which were known as the MX/MR series cars. The original Bentley sales literature outlined the key improvements that improved the overdrive cars performance which included the provision of an overdrive gearbox which would allow the car to attain a greater maximum speed without exceeding maximum engine revolutions. The steering was of improved design, being lighter and providing greater control under all conditions. Modified gear ratios and slight engine modifications also improved acceleration under certain conditions. For the first time on a Derby Bentley, the radiator shutters were fixed in a static position as opposed to being thermostatically controlled. The slower running engine coupled with the over drive top gear resulted in greater silence and smoothness. And finally centralised chassis lubrication and automatic shock absorbers with over-riding hand control were fitted.
The MX/MR models were truly the ultimate incarnation on the Derby chassis and are still very much sought after some eighty-five years on. Just two hundred “overdrive” chassis were created, finding their way to lucky owners with a variety of coachwork designs.
The Bentley 4 ¼ Litre is considered to be one of the finest examples of pre-war British luxury and craftsmanship. The combination of Rolls-Royce engineering and Bentley's sporty heritage resulted in a vehicle that offered both high performance and refinement. The car was a favourite among wealthy drivers who appreciated its elegant design, superior build quality, and driving dynamics. The Bentley 4 ¼ Litre is notable for its significance in Bentley’s Pre-World War II history, showcasing the brand's prestige, craftsmanship, and engineering capabilities during the interwar years.
Thoughts from Frank Dale
The Bentley 4 ¼ Litre is a key part of Bentley's pre-war history, showcasing a transition from the early, racing-oriented Bentleys to a more refined and luxurious image and motor car under Rolls-Royce's ownership. It remains an iconic model, admired for its elegant design, powerful engine, and high-quality construction.
The survival rate of these motor cars almost ninety years on is nothing short of remarkable, testament to the level of craftsmanship employed at their inception. A drive in a nicely sorted 4 ¼ Litre model, especially and MX/MR series car, is a wonderful experience, even more so if the car has open lightweight coachwork. They are exceptional motor cars. One of my absolute favourite motoring memories is taking Honeysuckle, a 1939 4 ¼ Litre overdrive model with open tourer coachwork by Vanden Plas to Pebble Beach in 2019. Taking part in the Rolex Tour on Thursday, driving the car from the heart of Monterey, south along the coastal road to Big Sur was simply amazing, a memory I will always cherish.