An oddity that Cecil Wickham committed to film during the 1933 Century of Progress Exposition was the Autotram. This self-propelled passenger vehicle was made by the Clark Equipment Company of Battle Creek, Michigan. The body was of aluminum and the power was supplied by a 16-cylinder gasoline engine with a hydraulic clutch. On the postcard below, distributed at the Century of Progress but only more recently acquired by me, the builders claimed the Autotram was capable of 100-mile-per-hour speeds. This model carried 40 passengers, and the Clark firm advertised a larger model seating 72.
The manufacturer was promoting the Autotram to railroads hoping to stem the loss of passenger revenue on lightly patronized lines, where a fully crewed train with locomotive and cars would have been a money-losing operation. I have no knowledge of how many were ever built, nor have I ever read of its being used in actual revenue service. However, I have learned that The History Center at Courthouse Square in Berrien Springs, Michigan, has published a 68-page illustrated history of the Clark Autotram.
Additionally, viewer Jamie Davis spotted a 1932 U.S. news clip reproduced on British Pathé, The Torpedo Car, showing the Autotram in operation — perhaps in a demonstration run (over weedgrown branch line trackage) rather than actual commercial usage. If other viewers have further information about this rarity, I would be glad to hear from you. Just e-mail firstname.lastname@example.org.