Which car to buy?

After about a decade of living car-free, the time has come for us to buy a car. So far, we've been happily living with public transportation, walking, and using the local car-sharing organizations for the occasional drive (due to where we've lived in the last 5 years, I'm a member of FlexCar, Philly CarSharing and ZipCar!).

I'll continue to walk to work while "Anita Job" will need to drive since public transportation is just barely out-of-reach at her new job (there are multiple reasons for this that I won't bore you with, but suffice it to say: we're buying a car on a whim).

The car will be used primarily for low-speed, single-occupancy commuting on well-maintained and plowed roads (about 20 - 30 min. each way) so putting a bunch of metal around the driver for the sake of safety isn't that important. Of course fuel efficiency is.

In the course of shopping around yesterday, we realized that certain models we previously thought out of reach could actually be affordable to us...some via lease, some by purchasing used, but they are within reach. We're down to deciding between a VW (likely a Jetta), a Mini, and possibly a Prius with the Jetta being the most affordable yet least fuel efficient car of the group, and the Prius being the opposite: least affordable and most fuel efficient.

Any opinions about those? Have we left any other options out?