The Riley MPH is a two-seat sports from British Motor Corporation, built from 1934 to 1935, when streamlining and independent suspension were arriving together. Under the bonnet: 1.4, 1.6 or 1.7  .
The background
The Riley MPH is a small production, two-seat sports car made between 1934 and 1935 by the Riley company of Coventry, England. Very few were made, and examples are now highly sought after. The chassis, with half-elliptic springs and rigid axles front and rear, was based on that of the car prepared for the 1933 TT races. To keep the height down to as low as possible, the side members were positioned under the axle at the rear. Large, fifteen-inch drum brakes were used. The bodywork was mainly made of aluminium, built over a traditional wood frame, and featured a long bonnet, front wings flowing into running boards and a short, rounded tail. The windscreen could fold flat to reduce air resistance. A choice of three sizes of the six-cylinder engine was available, 1458 cc, 1633 cc or 1726 cc fitted with triple or more usually twin SU carburettors.
The engines had the traditional Riley arrangement of twin camshafts mounted high in the crankcase. Aluminium alloy connecting rods were used. The 1726 engine had an output of 56.8 PS (56.0 bhp) (41.8 kW) at 4800 rpm. Drive was to the rear wheels through a choice of either a four-speed manual "crash" gear box or an ENV pre-selector gearbox supplied by Armstrong Siddeley. The top speed of the 17 hp (1726 cc) engined version was approximately 90 mph (145 km/h). The exact number made is not known, but is believed to be around 15, and it was expensive at £550. Numerous replicas have, however, been made. Fourteen original cars are thought to survive.
The engineering
Power comes from 1.4, 1.6 or 1.7  . It weighs 914 kg. It shifts through a 4-speed manual or preselector. The wheelbase is 97.5 inches (2477 mm). These are manufacturer figures carried by Wikipedia and Wikidata, not road-test measurements.
Where it sits
Its family tree is legible: it took over from the none; its successor was the Riley Sprite. Its contemporaries in the catalogue — the Chevrolet Suburban, the Bugatti Type 57, the Triumph Dolomite — show what else the money bought that year. Its British Motor Corporation stablemates include the Austin 10 and the Austin 12.
What it costs now
There is no federal ownership record for the Riley MPH — 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.