[lsllc]

I don't think that many are. Most people I know who live within ~3 miles use the T, bike, walk, bus or even rollerblade! (parking is expensive in the city). It's the middle to outer 'burbs that have to drive (unless you live on the commuter rail).

Interestingly, plenty of people who live in towns on the commuter rail do use it, but they all complain about packed trains, crappy service when it snows and of course if you miss one, you're waiting another hour for the next.