I believe the overall average is closer 21mpg than 25mpg
You also need to factor in the cost of accidents that kill and maim. I doubt cycling would be nearly as deadly nor as expensive to society. The best number I can find are ~40,000 deaths a year, 2.9 million injuries and a cost to society of around $169 billion usd. The number of fatalities and the number of accidents have been dropping, but I suspect the dollar figure is not due to inflation.
Aaron
