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Paul Souders vs. a 2008 Subaru Forester

Published 2008-06-02

(A Quick Back-of-the-Envelope Calculation)

  • Pm = price of a gallon of Alpenrose 2% milk at New Seasons = $3.89
  • Pr = price of a gallon (16 cups) of cooked white rice at New Seasons[1] = $0.35
  • Dfg = mileage of our 2008 Subaru Forester (standard transmission) during a typical week of commuting = 24.5 mpg
  • Eg = energy equivalent of a gallon of gasoline = 31,000 kcal (aka “calories”)
  • Em = energy equivalent of a gallon of 2% milk = 1952 kcal
  • Er = energy equivalent of a gallon (16 cups) of cooked white rice = 4256 kcal
  • p = energy I burn in one hour riding my bike on a flat road with no wind at 15 mph[2] = 704 kcal
  • Dpg = my mileage if I could somehow consume a gallon of gasoline = (Eg/p) × 15 = 660.5 mpg
  • Dpm = my mileage on a gallon of 2% milk = (Em/p) × 15 = 41 mpg
  • Dpr = my mileage on a gallon of cooked white rice = (Er/p) × 15 = 90.7 mpg
  • Cfg = cost to drive the Forester one mile = Pg/Dfg = $0.17
  • Cpg = cost to ride my bike one mile if I could somehow consume gasoline = Pg/Dpg< $0.01 (greater than half a significant digit [$0.005]
  • Cpm = cost to ride my bike one mile powered by milk = Pm/Dpm = $0.09
  • Cpr = cost to ride my bike one mile powered by rice = Pr/Dpr< $0.01 (less than half a significant digit [$0.005]

Notes

[1] Assumes 2 cups of cooked rice = 1 cup dry rice weighing 8oz
[2] A pretty leisurely speed for me under those conditions, so I might actually burn fewer calories than this, i.e. get better “gas mileage”