For CA Bay Area car-free people...
 

If you're car-free but need a cheap way of borrowing a car for an errand here or there, you should check out this: http://www.citycarshare.org/

I signed up for it and did the orientation last night. It's $4 an hour and 44 cents a mile. You don't pay for gas or insurance or cleaning unless you're the one that made it dirty. That's it. They give you an electronic key to get into the car and there are reserved spots all over SF and the Oakland/Berkeley area. I haven't used it yet but I'm looking forward to trying it out.

If you really do want to join, you can get a $20 credit if you say someone referred you. If you want to say I did, my member number is 7635. ;)

Wow, not sure they're any cheaper than hertz/avis/enterprise.......

I think Zipcar is something similar. They are available in Boston, NYC, DC and more. I've seen their vehicles around (especially at Ikea) so clearly, people like the idea. I've not used their services so I can't offer any review. But where else are you going to get to rent a MINI to go screaming through curves for cheap? ;)

You'd rent from hertz/avis/enterprise if you wanted a car for a 24 hour block since they charge by the day. This is if you need a car for a short amount of time, like an hour or two to just run an errand. Two advantages with CityCarShare is that 1)you can rent electric/hybrid cars and trucks it doesn't cost more for you to pick which car you rent, and 2)you can pick up and drop off the car whenever you want 24 hours a day, 7 days a week, not when the car rental place is open. Plus, you can literally stand in front of the car, call the number, reserve on the phone, open it with the fob and go immediately. This complete independance is why I like it.

Exactly the same thing, just the SF Bay Area version. This company started in 2001.