That's cool, it's not for everybody! Glad you found something you liked.
Note to author: You are not too stupid for actual science. Maybe, like a lot of young women, you were subtly steered away from science. Maybe you like it, but you don't want to do it as a career. It's totally legit to choose not to go in that direction, but do be careful that your self-deprecation isn't reinforcing the message to young women that science isn't for them.
k sorry, but I have to call bs on this one. I just don't think your car-less comparison costs are reasonable. 1) It doesn't seem likely that you'd need a car once a week, given your description of where you live. 2) When you did need a car for errands or other short-term use, you probably wouldn't be paying Zipcar's daily rate (which *is* super expensive). You'd just reserve the Zipcar for the few hours you needed to run your errands. 3) For long trips (weekend or more), a regular rental car is usually considerably cheaper than Zipcar. A quick search on Kayak shows rental cars for $40 / day this weekend in SF. I'm not hardcore anti-car over here (have one, in LA; lived without in New York, NJ, and Berkeley). Even in cities with great public transit, cars give you some extra freedom and convenience for sure. And your car sounds awesome! But if you're going to look at straight-up cost comparison, I think you have to assume you'd be a smart no-car consumer.