Background
The 20/25 was the second of Rolls-Royce’s pre-war entry level models, and had considerably more get up and go than its predecessor, the 20, thanks to a bigger, more powerful, 3.7-litre engine.
Built between 1929 and 1936, the 20/25 was tremendously popular, becoming the biggest selling of the inter-war cars built by the world-famous Crewe-based company.
Its success enabled Rolls-Royce to survive the economic difficulties of the Great Depression years and remain one of world's great brands.
A total of 3,827 20/25s were produced, of which a staggering 70% are still on the road today.
An Autocar report in 1931 describes the 20/25 thus: 'Every single feature spells durability, the machine is on a plane altogether superior to the normal style of motor car'.
All 20/25s were outfitted with custom bodies from legendary coachbuilders such as Park Ward, Vanden Plas, Hooper, Freestone and Webb, Brewster, Gurney Nutting, Thrupp & Maberly, Mulliner, Rippon Bros, Windovers, and Cockshoot.
The engine was a 3699cc straight-six with overhead pushrod operated valves, featuring a cast-iron block with an aluminium crankcase. A single cast iron cylinder head sat atop the assembly with a single spark plug per cylinder.
The typically British long stroke design also incorporated a seven main bearing crankshaft with a vibration damper and pressure fed lubrication, with a relief valve feeding the rocker shaft and timing gears. All of which was really very advanced for the time.
Mated to this was a four-speed manual gearbox with synchromesh on third and fourth gears, and a single plate dry clutch. These features, plus servo-assisted brakes on all four wheels, ensured that Rolls-Royce were pretty much leading the way in the development and application of new technology.
In 1932 shock absorbers and a thermostat-controlled cooling system were introduced. The thermostats operated the radiator air-flow automatically, eliminating the need for the driver to open and close the radiator shutters by hand.
In 1936 the 20/25 was superseded by the 25/30.








