To car or not to car?

I have at least until the end of the summer to actually decide, but I've been flip-flopping on whether or not to replace the intrepid snowflake, who (which?) I sold back in atl. Getting around the city without a car is pretty manageable, but getting to and from work without one is a challenge. When I first moved out here a month ago I lived within a couple of miles of three coworkers who all had cars and all drove to work, with whom I could carpool. By September I'll be down to one (boss just moved across the bay and one coworker is leaving at the end of the summer to go back to school). So initially I was thinking, ok, buy a car as soon as I have the capital set aside, goal Sept. 1. But then I sort of stopped missing having a car. And this week I have the luxury of borrowing my intern's car while she's out of the country for ten days, and frankly I haven't really had the impulse to drive it much. I drove to work yesterday, and found the commute way more exhausting than when I'm a passive (but, hopefully, entertaining) passenger. Sure, it would probably be less exhausting if I was driving my own car instead of having the added stress of worrying about someone else's car and not really being sure where the edges of it are for things like passing and parking, but still.

It takes a lot longer to ride the bus-train combo to work, but I'm thinking it still might be preferable. Plus, I could technically start my work day on the train, as it would be easy enough to start work while still en route.

And there's not much besides driving to work and road trips out of the city for which I think I would want a car. Most of the places, at least so far, that I've been interested in exploring would be a huge hassle to drive to but are readily accessible via public transit or my own two feet. And given that I only go in to the office two or three times a week, and already plan to be out of town for at least 3.5 of the next 7 weeks, how much should I really allow my work commute to dictate my transportation choices?

I hammered out a very rough estimate of the cost of a car, and I'm guessing that with renting out the parking space in my building and insurance and a monthly car payment, I'm looking at at least $700-$800 a month (and that's not including gas or other maintenance).

A similarly rough budget estimate for zipcar membership, five round trip bus rides a week, two round trips to work a week, with the help of my company's public transit subsidy still leaves me with an extra $500 a month for taxi rides and car rentals before I start to hit similar numbers to the car budget. So public transit is looking more and more appealing.

On the other hand, maybe a 90 minute commute (minimum, probably often closer to two hours) on bus and train would slowly make me crazy, something I can't really assign a dollar amount to. And there are some neighborhoods in the city that aren't really accessible without a car, so my priorities may change if/when it comes time to move.

So those are my thoughts so far. Thoughts from the peanut gallery?