This exact info was brought up in the UT Bike Summit that happened a few months ago. The presenter spoke a lot on the effect of inactivity and what the costs are to communities and to the individual. Getting rid of your car may not be the answer. Trying to replace all trips within 2 miles of your house with a bicycle may be a step in the right direction. Check out the 2 mile challenge (just type in your address and see what is within two miles) and, the Clear Air Challenge for more on what you can do. You can read the full report here. As always expensive and complicated issues being solved by something as simple as riding your wonderful bicycle.