British Motor Corporation does not build many cars like the Riley RM: a 4-door sedan (car) / saloon / 2-door Roadster (automobile) / open 2 or 3-seater / 2-door 4-seater convertible (car) / cabriolet with 1.5 L Straight-4 as for 2.5-litre Big Four but bore 69mm by stroke 100mm and bhp 60 @5,300 rpm, built from 1945 to 1955 in a decade split by war, when civilian production stopped and restarted.
How it came about
The Riley RM is a series of executive cars and compact executive cars that were made by Riley Motors from 1945 until 1955. They were the last models developed independently by Riley before its parent company, Nuffield, merged with Austin to form BMC. The RM series was produced in Coventry until 1949, when production moved to the MG works at Abingdon. Until 1952, models were marketed as the Riley 1½ Litre and the Riley 2½ Litre. The term RM has been used retrospectively to encompass models produced before 1952. There were four types of RM vehicles produced.
All used Riley engines with four cylinders in-line, hemispherical combustion chambers and twin camshafts mounted high at the sides of the cylinder block. The RMA was a large saloon, and was replaced by the RME. Both used a 1.5 L (1,496 cc) 12 hp (8.9 kW) (RAC Rating), developed before WWII. The RMB was a longer car, and it was replaced by the RMF. Both cars used a larger engine, new in 1937, a 2.5 L (2,443 cc) 16 hp (12 kW) (RAC Rating) "Big Four". The RMC and RMD were limited-production cars, an open 2 or 3-seater Roadster and a 4-seater drophead. The Riley Pathfinder was the RMH, and was the last saloon to be built with the Riley Big Four engine.
The hardware
Under the skin sits 1.5 L Straight-4 as for 2.5-litre Big Four but bore 69mm by stroke 100mm and bhp 60 @5,300 rpm. The layout matters: a front engine drives the rear wheels, the classic proportion — long bonnet, cabin set back — that most people picture when they picture a sports saloon or a grand tourer. The wheelbase is 1.5 L cars – 112 in / 2.5 L cars – 119 in. These are manufacturer figures carried by Wikipedia and Wikidata, not road-test measurements.
Family and rivals
Where it sits in British Motor Corporation's history is not in doubt: the Riley Kestrel body / and / Riley 12/4 / 12/4 1½-litre engine / or / Riley 16 / 16/4 2½-litre Big Four engine came before it; the Riley Pathfinder followed it; it was built at Coventry, England. On a showroom list of its day it stood against the Porsche 356, the Citroën 2CV, the GAZ GAZ-M20 Pobeda. Its British Motor Corporation stablemates include the Austin 10 and the Austin 12.
The money
There is no federal ownership record for the Riley RM — it predates the complaint database or was never sold in the United States — so MotorJury publishes no running-cost figure for it. For a car of this age the price is set by the collector market and the condition of the individual example, not by a formula.