He is a car salesman and race car driver by profession. He owns a European Imported Car dealership and sells Herbie to Jim Douglas. He was discovering that Jim was winning by Herbie and wanted to dispose of him.
When Mr. Wu meets him, Thorndyke bargins with Wu if he wins, Thorndyke can have Herbie. But if Dougalas wins, Wu can have his shop, and Dougalas won. Throndyke is now a mechanic in Wu's Car Shop. Despite his villianous character, Thorndyke appears to be a very skilled racing driver, finishing behind only Douglas in the various races in the movie. He also wins the race before the El Dorado event.
His most famous car is a yellow GT car he calls the "Thorndyke Special", which is actually an Apollo 3500 GT. He also drives a Ferrari and a Jaguar in various races in the film.
Although, never specifically mentioned in the movie, Thorndyke appears to be British, as he speaks with a thick British accent.