[frankus]

The math on walking, at least, seems little off: 210 calories per hour divided by 2.5 miles per hour is 84 calories per mile, which is about 23.5¢ per mile.

Also the cost of driving should really use the average fleet fuel economy of a country together with the fuel price in that country. That works out to a hair under 10¢ per mile for 2014 fuel economy and today's gas prices.

The takeaways remain the same, though: Human-powered transportation isn't especially efficient (unless you're burning calories you would have eaten anyway), and driving is subsidized up the wazoo in the US.

[dietrichepp]

I think the math should also include cost of auto infrastructure, vehicle deprecation, and the reduced health care costs if you walk.