Getting a Car?

Lately--at the prompting of friends, coworkers and close advisors I've been seriously considering acquiring a car.
I got back from a weekend to Williamsburg where a good friend lent me his car for the weekend. Not only was I able to stay much longer than usual--I also had the freedom of leaving at 8:30pm Friday night, and arriving in Williamsburg in almost 2 hours! During the weekend I got to see some missionary friends from Louisiana in Richmond--without the car, this wouldn't have happened.

This is something that's left me very conflicted....let me explain.

Reasons in the pro-column:
-It would ease my commute back home late nights from campus from about 1.5 hours to about 20 minutes. This would be safer sometimes--but also just improve general quality of life. Getting home at 10:30pm is much more pleasant than 12am in terms of my sleep.
-But also the sheer blessing that a car can be to others--I find often the only thing I ever need to ask others for is a ride. With a car, I could be very giving with the car--allowing students to borrow it, giving people rides to target, carrying supplies to campus, moving things from the house.

However, many reasons some together that convict me about not getting a car...
--Cost. I find it to be an issue of stewardship right now with my resources. Having a car would likely raise my monthly expenses by at least 33%--currently I have that money to spend. I probably would still end up taking the metro to work most days so that money would not necessarily all be rechannelled.
--Having my own vehicle--like the other 3 vehicles our hosue already has, would in some ways only allow me to be even more independent and evade community, getting to come and go as I please.
--parking. In georgetown, parking near campus I'd literally have to move the car every 2 hours to avoid getting a parking ticket--on a day-to-day basis this is simply not practical.
--I moved to the city to avoid having a car--at the cost of higher rent, inconvenient parking.
--Environmental issues--I am concerned about the witness of just adding another carbon dioxide producing box to the system--shouldn't I be instead buying into these systems like zipcar or things like that?
--This weekend I got to borrow a car--there are many instances, where I could enter into similar car sharing arrangements with others. This would keep us likely more dependent on others and would better utilize a resource that every single person doesn't necessarily have to own for themselves.

Just some of the thoughts swimming in my head, please add an other thoughts in the pro or con box.