[fpgaminer]

The article touches on this, but doesn't directly address it: whether they're using gross calories or net calories. Gross is the total calories you burn during that mile. Net is how many additional calories you are burning as a result of walking versus being sedentary.

Glancing at the wikipedia article which the author uses doesn't clarify this, nor does Wikipedia's citation. I didn't check the citation's citation.

Clearly we want net calories. Average humans burn ~100 kcal per hour doing their normal activities during the day, so that could potential change the figure from 210 kcal per hour walking, to 110.

[mobiuscog]

This can't be mentioned enough, because otherwise the travelling by car would have to include the 'human' fuel element as well.