Basically, I signed up for an account with a credit card. You can also use a debit card. About a week later, your zipcard comes in the mail. This is a very important card, as it unlocks the car. The key is already in the car. This concept takes some getting used to if you have lived in the city all your life.
I like Zipcar when I am in San Francisco, but I LOVE it even more when I am traveling. I used to get online to rent a car before my trip. Then, take a shuttle to the rental car lot from the airport. Inevitably, the counter agent would try pressure me to buy $12-20 insurance per day, and a tankful of gas, neither of which I needed. The auto insurance and American Express takes care of the insurance. I would have to find a parking spot every few hours in a city that I am not familiar with, or pay $25-35 at the hotel per day. If I get a parking ticket, in some cities, it was $50. Sometimes, I would have to return the car before the end of the trip. This meant driving back to the airport, remembering to find a gas station and filling up the tank (or be charge over $4 per gallon, and taking a shuttle back to the airport and a train ride back to the city. With Zipcar, I rarely have to do that any more, and gas and insurance are included for $7-12 an hour.
One thing that I would like to mention Zipcar is a strong argument for location-based services for non-iPhone users. Although the website is great for reserving cars, if I have to reserve a card by your Blackberry it is cumbersome. I cannot be sure the exact time when I need a car, and some times I like to reorder my errands. One day, I had to go through seemingly, all the neighborhoods in Chicago. I don’t know the demarkation of each neighborhood that well so this was not that easy and there are a lot of neighborhoods in Chicago. I had to scroll through all Zipcar locations the neighborhood. I had to scroll through all of available cars. My Blackberry can pinpoint my location on Google maps, and I was standing right next to the car that I wanted to rent. Some day, the marriage of Zipcars and location-based services would be a perfect match. Nevertheless, ZipCar is already a tremendous advancement.