car2go is a popular car sharing service that is in 26 major cities, including Austin.  You must be a member to drive their cars, so see their website for details.  You can take any of the car2gos you find distributed around the spot or book online 30 minutes before you want to drive. That way you can save yourself the wait and get to your destination faster. At your destination you can either leave the vehicle, or go back to it if you want to drive further.  You only pay for the time you use the cars.  Car locations can be found via their website, their app or simply while walking around.  The big plus about this service is how easy it is to park in the city.  Some areas downtown have specific spots designated only for car2go.