...earlier, you asked for "inputs" so here's a "blue-sky" one: How about an X-Y MPG waterfall chart with a star marking where YOUR car falls in the continuum of MPG values...with the bubbled wording: "You are HERE"

Make the chart a single, universal valued creation, with the X-Y "starred" location being determined by the persons MPG value.

DOn't ask me about multiple-vehicle people...uh, maybe multiple stars?

Old Tele man
Tucson, AZ USA.