Back to the topic at hand, The original Auto Train Corporation service was popular from the get go, and initially profitable.
One thing that Auto Train was not known for was it's food. The service for most of it's existence was a buffet style dinner, served in one of the converted dining cars it purchased. Purple Plum was the name given to the buffet cars, the food was often described as mediocre.
There was a great article on the original Auto Train that ran in Trains, about 15, or so, years ago, and the author talked about the various venders that were used for food service, Marriot being one of them. With Senior Citizen snow birds among it's most loyal riders, any change in food vendors could set off issues, and the author goes into detail on the results.
In the later 70's, there was an attempt to upgrade dining services, and a switch to table service was made (see menu), I do not know if this
was the Marriot period, or not.
Ken