I have never been car free, but in the last two years, I realized how much less I drive than most of my friends and it is intentional, too. I fill my car up once every 10 days to two weeks. Of course, some of this is because on the weekends, if we go out, we usually do not take my car, but still... it's made a significant drop in my gas expenses. This week I have to drive to Newton, twice (suburb next to the city), so there goes my budget for this week. I plan my errands and everything is done within a five-seven mile radius. In the summer, I go to a lot of appointments and some small shopping by bike. I could do more here. In the last four years that I worked, I rode my bike to work twice a week, for the last two months of the school year and in September. It's not really feasible for me to do a full grocery shopping trip on a bike; the closest one is 3.5 miles, but it's up a big hill on the way there and on the way back. My commuting bike only has one pannier, not really meant for shopping. I do go to Trader Joe's, farms for produce, etc. on it.
I couldn't live without a car, but I have lessened my dependence.