The good thing about Car2go is that there is no annual fee. You will pay membership fee of 35 dollars only once and that's it. You will get minutes for filling up the car as a bonus too. Also you can use it as a one way ride. You don't have to return it from where you picked it up.
The disadvantage of it is that it is only in specific locations available, usually downtown cores.
Use the following code till August 30th and you will not only get the membership free but you will be given 30 minutes of free ride.