It seems during WW I at least one Russian Red Cross train had some motor vehicals attached to it. The cars had the head of the trains motto Semper Idem or Wem painted in large red letters on them. The head of this train was Vladimir M Purishkevich best known for his role in the murder of Rasputin. The car used to transport Rasputin to the Moika Palace where he was murdered was from this train. The motto was painted over with khaki paint right before the murder and loaded back on this train right afterwards. In Purishkevich's wiki bio there is a picture of part of the train. The book "Diary of the Commander of the Russian Imperial Guard" refers to it as huge. The book "Russian Hussar" mentions a visit to this train for a bath.
Train car colors in Czarist Russia 1st class cars blue 2nd class cars yellow 3rd class cars green. The Tsar's Imperial train cars were also painted blue. One of the hospital trains sponsored by the Empress Alexandra the cars were painted blue with white roofs until the train was bombed when the roofs were repainted khaki.
I hope this is of some interest the info on the cars on Purishkevich's train was from his book "The Murder of Rasputin"
