To be honest I'm very disappointed with the responses so far!

It's totally doable to live in Austin without a car.

There's lots of nice neighborhoods in Central Austin with access to supermarkets and your work.

The bus system in Austin is great for a city its size, and it is easy to get to the airport or get around if your bike is broke or the weather is really ****ty.

Also, after biking around San Francisco this summer for a day, I've got to say that the hills there were a lot more intense than in Austin. There are some steep Austin hills, but they are generally pretty short and easily avoided. You usually just have to deal with a slight upgrade or downgrade in topography but nothing brutal.

So yeah, I would recommend finding a place to live in the following zipcodes:

http://www.city-data.com/zipmaps/Austin-Texas.html

78705 (lots of undergrads)
78751
78756
78757 (south of US HWY 183)
78722
78701
78702
78704 (weird South Austin, lots of culture here, in a good way, if you are 420 friendly)
78703

I-35 is the line of racial segregation present in most cities but the east side is being rapidly gentrified with white hipsters. however, there are some good projects being built and a lot of nice authentic hispanic culture.