Last October, I moved from Atlanta, GA where I had a 45-90 minute commute EACH way to work, to Washington, DC. Upon moving, I sold my more or less brand new Mazda 3S and now rely solely on DC public transit or walking/riding my bike.
Why?
Well, I live in the District, so I can easily walk 15 minutes to one of two Metro stations on the Red Line.
I honestly cannot afford a car / insurance, gas, and maintenance considering the cost of living increases experienced from Atlanta to DC.
(Well, I could but I wouldn?t be able to save / invest as much.)
I could not afford a garage, so my brand new car (my baby) would have been exposed to some really crappy elements.
My commute is now roughly 25 minutes each way (15 minute walk + 10 minute Metro train ride).
I now get at least a small dose of exercise during my commute, so it is healthier if you don't consider the air/smog intake.
The commute is far less stressful. I tune in to my music as I walk down the sidewalk.
Sometimes I ride my bike to work, and that can actually be fun (without music).
Not having a car / using public transport is environmentally friendlier.
I have the chance to read in the morning while on the train.
The train gives you the opportunity to socialize to some extent with members of your community.
I don't have the stress of car maintenance, oil, tires, batteries, and sweating as I watch oil prices reach $80.00/barrel.
I now pay only around $180/year for an EXTREMELY good USAA non-owners auto insurance policy.
And last but not least, I now subsidize OPEC/Terrorism to a lesser extent.
On those rare days I need a car to make a trip to IKEA or visit colleagues or friends who live outside of the Metro's reach, I can always get a rental car for around $40/day or a ZipCar/FlexCar for around $8/hour. No big deal.
My Giant grocery store, dry cleaners, barber, Starbucks, restaurants, etc. are all across the street from my apartment.
Edit: Couple of things to add:
Parking in DC is simply a bitch.
Traffic is no good either, especially if you need the beltway & beyond.
Do I miss driving those fun roads with a manual tranny? Yes, often! But I still have a Miata in my dad's garage that I can drive when I go back home.