how do I make vehicles smoke?

[Bus 584 UFT]

I have seen some vehicles producing black smoke, how do I make them do that?

 

[VerkaN]

this should do
exhausts
;ref node, direction node, factor material
103, 99, 1 default
105, 98, 1 default

more on it here: https://docs.rigsofrods.org/vehicle-creation/fileformat-truck/#exhausts