# Paul Souders vs. a 2008 Subaru Forester

##### Published 2008-06-02

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

- P
_{m}= price of a gallon of Alpenrose 2% milk at New Seasons =**$3.89** - P
_{r}= price of a gallon (16 cups) of cooked white rice at New Seasons^{[1]}=**$0.35** - D
_{fg}= mileage of our 2008 Subaru Forester (standard transmission) during a typical week of commuting =**24.5 mpg** - E
_{g}= energy equivalent of a gallon of gasoline =**31,000 kcal**(aka “calories”) - E
_{m}= energy equivalent of a gallon of 2% milk =**1952 kcal** - E
_{r}= 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** - D
_{pg}= my mileage if I could somehow consume a gallon of gasoline = (E_{g}/p) × 15 =**660.5 mpg** - D
_{pm}= my mileage on a gallon of 2% milk = (E_{m}/p) × 15 =**41 mpg** - D
_{pr}= my mileage on a gallon of cooked white rice = (E_{r}/p) × 15 =**90.7 mpg** - C
_{fg}= cost to drive the Forester one mile = P_{g}/D_{fg}=**$0.17** - C
_{pg}= cost to ride my bike one mile if I could somehow consume gasoline = P_{g}/D_{pg}**< $0.01**(greater than half a significant digit [$0.005] - C
_{pm}= cost to ride my bike one mile powered by milk = P_{m}/D_{pm}=**$0.09** - C
_{pr}= cost to ride my bike one mile powered by rice = P_{r}/D_{pr}**< $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”