The Riley Nine was one of the most successful rear-wheel drive lightweight sports cars produced in the interwar period from 1926 to 1938. It was designed largely by the Riley brothers, Percy and Stanley. Stanley was responsible for the chassis, suspension and bodywork and Percy designed the engine.

At launch, the car was available as a 2-seat sedan and 4-seat tourer. The sedan was able to reach a speed of 97 km/h with a fuel consumption of 7.1 l/100 km. As time went on, new body styles were created as customers became more and more demanding, waiting for new improvements. The car was powered by a litre 4-cylinder I4 engine, the power of which was gradually increased.