The Bentley 4 Litre was a motor car built on rolling chassis made by Bentley Motors Limited in 1931. The 4-litre chassis was conceived and built in a failed attempt to restore Bentley to a good financial state. Announced 15 May 1931, it used a modified 4-litre Ricardo IOE engine in a shortened 8 Litre chassis at two-thirds of the price of the 8 Litre in an attempt to compete with the Rolls-Royce 20/25. Instead, Bentley went into receivership shortly afterward, from which it was purchased by Rolls-Royce Limited.
The conventional straight-6 engine used an 85 mm bore and a 115 mm stroke for a total displacement of 3.9 l and a power output of 120 bhp at 4,000 rpm. The engine power was not suitable for the heavy chassis.