Car No. 54 is air conditioned and sleeps ten. It has a finely furnished rosewood and cherry-paneled interior containing an observation/drawing room, two staterooms, a dining room, secretary's room, porter's room, two bathrooms and a kitchen. The kitchen includes a gas stove and a refrigerator.

The car was originally built by Barney & Smith in 1914 for the Soo Line Railroad as Buffet-Baggage combination car No. 1704. In 1927 it was rebuilt into Business Car No. 54. In 1962, the Soo Line railroad sold the car to private owners who brought it to Southern California, keeping it at the Santa Fe station in San Bernardino for a period of years. It was repainted from its Soo Line maroon color scheme into its current blue at the adjacent Santa Fe shops. It was named 'Mt. Rubidoux' after the mountain-top in nearby Riverside, California, which was famous for its Easter Sunday celebrations.

The car is still used during special events at the Museum. It is pictured above on display at the Riverside Metrolink station in 1995.