It's also complicated by the fact that for some people, a larger sized vehicle is not only appropriate but necessary, for large familes, for work, etc.  Also, some larger-sized vehicles may get significantly better mileage than others.  (After putting a lot of thought into it, my father bought a Volkswagen Vanagon shortly after my brother -- the last of four kids -- was born in the early 80s.  It seems it got fairly good mileage.)  If sheer size is used as a rule of thumb for sizing up the fuel efficiency of vehicles on the road (or conversely, wreckless consumption of their drivers), those distinctions will be overlooked.

Truth unfolds in time through a communal process.