My '93 Jeep Cherokee just spent a week in the shop, and while I live in the city where I can walk to and from work, it did start to become inconvenient not to have a backup car. So I signed up for Zipcar.
It's pretty simple, you reserve the car online, and your Zipcard unlocks the door. The key is connected to the dash with a retractable cable, you start the car and go. You're supposed to gas the Zipcar up if it gets below a 1/4 tank, and they provide a fuel card for that, but I didn't get that far with it.
You can also find and reserve a car with your mobile smartphone, use your phone to sound the horn and unlock the doors, and send a text to extend your return time if no one has it reserved immediately after you.
Below are the Zipcars in my neighborhood. The first two are just two blocks away, the other dozen are within a half mile. There are also 14 Zipcars within a block of where I work. Zipcar also has vans to rent, but I would have to walk a little farther.
Kia Soul "Shur"
Nissan Sentra "Spelts"
Honda Insight Hybrid "Hadassah"
Mazda 3 "Mcgillis"
Audi A3 "Austria"
Nissan Sentra "Dionte"
Kia Soul "Sotto"
Honda Civic "Crysta"
Toyota Tacoma Pickup "Tzeremes"
Mazda 3 Hatch "Maragno"
Nissan Sentra "Skoczen"
Fiat 500 "Rachelle"
Toyota Prius "Pasquale"
Ford Escape "Elsa"
Some aspects of the Zipcar service are annoyingly cute, like giving all the cars names. I can learn to live with that.
I applied online ($85 to sign up) on Tuesday and got my Zipcard on Friday (Wednesday was July 4th, a holiday). The cost is $8 to $12 per hour depending on model, or $4 to $6 per hour at off-peak times in the middle of the night. Perfect for a 2 am grocery store run.
I am expecting my Jeep to give out in the next couple of years. Zipcar could move up from backup car to primary car.