For a very good fictionalised account of the use of the Model T in Mexico read "The Tin Lizzie Troop" This is based on a real volunteer cavalry unit of rich Americans (many of them undergraduaduates from one of the Ivy League universities) who provided their own transport and chose cars instead of horses, the dialogue is fictionalised but the events real. I think the author's name was Schwartztout or something similar (doesn't one become ignorant when seperated from one's library?).
I'm interested in the fact that the guys in the photo are using Lewis guns. Despite being an American invention most production at the time was in Birmingham UK. US forces favouring the Colt Mg. (This attitude changed a bit when the US got involved in the real war). The Lewis seems to have been very much favoured by volunteers and the like who financed their own armaments.