From memory, a bit of history which probably isn't too far off being right.
The real Chitty was a 20's racer with a huge engine, run by a Polish Count.
For the film of the Ian Fleming book (yes, 007) between 3 & 5 cars were built, each one for a specific purpose. The runners were based on a Ford Transit chassis ( Thats a similar vehicle to a 60's Econoline, for those of you over the pond) Motive power was, I think, either a V4 or straight six. I also seem to remember that around two of the cars still exist, One is in a car museum in the North of England, or it was last time I read about the place, called 'Cars of the Stars'. A couple of years ago, Corgi rereleased their diecast 1/43rd scale model of Chitty, it might still be available, not cheap though.
Pete