At first the RAC rating was usually representative of the car's actual (brake) horsepower, but as engine design and technology progressed in the 1920s and 1930s these two figures began to drift apart, with an engine making much more power than its RAC rating (and the car's model name) suggested: by 1924 the Austin Seven's 747 cc engine produced 10.5 brake horsepower, 50% more than its official rating.