13 engines is the maximum number for French legislation for an engine train.
Today has run this 13 engines-train between Nevers and Dijon that I caught near Santenay, Burgondy.
(Locs numbers : 75091, 75078, 75073, 69195, 69316, 69472, 66401, 69413, 69213, 69470, 67251, 75077, 67266)