Clark gained his revenge the following year, taking his first World Championship in the 25, by winning 7 races, Belgium, France, Holland, Britain, Italy, South Africa, and Mexico. Lotus also won its first constructors' championship. Following the United States GP, a 25 was taken to the Indianapolis Motor Speedway for evaluation, where they also trialled Lucas electronic ignition for Ford. The results were encouraging enough for Colin Chapman to mount his ultimately successful challenge on the Indianapolis 500.