I can easily walk to downtown Mill Valley or downtown Sausalito, and with a little more oomph to the top of the mountain. I would give myself a 100% score. I have lived here and, at times, rarely gotten into a car depending what is going on in my life. With a bicycle, I can get to San Francisco or San Rafael....
I see that the purpose of the site is to suggest places where you can live without a car. A score of 90 to 100% means you could live without a car. I checked a site at 67th and Broadway in Manhattan and it got 98%. One would not want a car if they lived in Manhattan...
I had a neighbor who did live here without a car.. She took a bus to the city and bought her groceries daily at the local grocery store, which is 6/10th of a mile, but to live here a car really is required.
Check out where you live:
http://www.walkscore.com/