The old "Sterling Diners" certainly had the general appearance of a railroad car. I remember there was one near Fairport NY and my brother's girl friend was a waitress there in the 1960's.
https://en.wikipedia.org/wiki/Diner
Inspired by the streamlined trains, and especially the Burlington Zephyr, Roland Stickney designed a diner in the shape of a streamlined train called the Sterling Streamliner in 1939.[1] Built by the J.B. Judkins coach company, who had built custom car bodies,[2] the Sterling and other diner production ceased in 1942 at the beginning of American involvement in World War II.