Warning, this subject is old (302 days without answer)
Ddey65
This is a late-1950s promotional film involving piggy back cars on railroads, specifically made by the Southern Pacific Railroad.
https://www.youtube.com/watch?v=I7AKoKEMe6w
No IMDb listing, but there are some nice trucks in this film. I'm not entirely sure of the copyright date on this, so I'll need to do more research.