I think dioramas are just supposed to be "lifelike." A snapshot of a moment in time or event. Then the question becomes can lifelike be a relative term (can a fictious character be lifelike)?
Try Maple City Hobbies 574-534-9661 or Fantasy Games 574-299-1133. Fantasy doesn't really deal with model cars, but some of the gaming groups that go there may be able to tell you a few clubs.