If you're not aware of the pioneering and very successful efforts of Philly CarShare to promote shared car ownership as a means to reduce the environmental impact of cars in the city, it's an interesting concept.

Their fleet consists mostly of reliable and fuel-efficient Toyotas and Hondas. Here is their xB page:

http://www.phillycarshare.org/html/fleet_ScionPage.htm

You can check out the rest of the site from there.

R