Starting with CN #501, CN experimented with a number of self-propelled passenger cars between September 1921 and 1925. They finally settled on the oil-electric as represented by CN #15820. The bodies were built by the Ottawa Car Company. The diesel engine was from Beardmore of Scotland (the same supplier for the first CN diesel), and the electrics were from Westinghouse. They were assembled at CNs Point St Charles shops. The proper term is "oil-electric" and not doodle-bug or gas-electric. They lasted well into the early 1950s before being replaced by the Budd RDC cars.
CN #15820, the first of the oil-electrics, was the first train to run non-stop across Canada in 1925. The story is quite interesting with a couple of near-miss accidents along the way. 15824 shown above was the 4th in the series of the final oil-electric model by CN.
The bodies of subsequent oil-electrics were built both by the Ottawa Car Company and by National Steel Car in Montreal and assemble at Pt St Charles. In the early 1970s, there was a book published on CNs oil electrics. Except for a few early experimental models between 1921 and 1925, I believe they were all built in Canada. The Bachmann "doodle-bug" is a close representation.
CP came into the oil-electric scene a little later on with most of their units being built by the car manufacturers such as EMC.
The "boxes" that sit on top of the oil-electrics above the engineer were added later on. These were radiators.
If you buy an "off-the-shelf" model such as the Bachmann, you'd have a pretty close representation as they were greatly modified over time.
