Via Rod Dreher, you can find it here: Consumer Consequences. Some of the assumptions seem to be a little off, but overall, it's a thought-provoking exercise. For the record, our family graded out at 3.6, which was far better than that top-hatted, styrofoam burning MSM plutocrat Dreher.
Where we ran into trouble was with transportation. Good luck finding light rail in Detroit, alas.