Zipcar
For the majority of Americans who own a car and ask, "What's Zipcar?", it's officially community car sharing for urbanites, or more de facto, car rental made easier, a little greener. Keep in mind, this is written from a New Yorker's perspective, where driving is more of a headache than most places in the US.
The two features that differentiates Zipcar from typical rental companies is that it rents by the hour and enables renters to pick up a car by just zapping a card on the windshield reader.
Typically, you call the garage an hour in advance to get the car ready. Once you zap your card, you're on the meter. You have 180 miles of free gas. Insurance is covered. The tolls incurred on the included EZPass will be transferred to your bill. Do your errands, visit your friends, return the car, zap the card and you're done. If you need more gas, there's a gas card that gets charged directly to Zipcar.
To join Zipcar, you need to have a clean driving record and I think that translates to no moving violations for x number of years. There's also a deposit of $300 required. It's been awhile since I joined, so my memory of these details might be murky. There are frequent usage plans that offer discounts.
What's the big deal?
It's convenient
If you've ever rented from one of the major players in New York, you know how long waiting on line and doing the paperwork can take. I've seen this process take an hour. I've waited up to 45 minutes. So to just walk up and pick up a car is like owning your own car and because of Zipcar, I did not buy a car and I imagine others did not either, although my neighbor opted to buy a car for the convenience of a nearby garage.
I found out auspiciously that Zipcar can unlock a car remotely when I locked myself out. Zipcar also sent a text message to my friend's cell phone when his car battery was close to dying because he left his lights on.
It's cheaper
It is if you don't go renting BMWs and the like. In Manhattan, a garage space is about $500 a month. I usually pay this much or less using Zipcar and I don't have the headache of maintaining a car. Gas and insurance is included in the price and daily rate is as good as, or better than Hertz, National or Avis. You can save even more money if you rent by the hour. If you rent a car for a day, you can repark the car in it's original garage, saving on the cost of Manhattan parking - this is a great plus if you rent on a weekday.
It's green
I can't cite the studies, but according to them, car sharing eases congestion in urban areas because fewer people own cars. And because fewer people buy cars, that intangibly saves resources because fewer cars are built - or something like that.
Now for the downsides.
Insurance coverage
One of the major complaints about Zipcar was it's weak insurance coverage. They've increased the 3rd party liability to $300,000 now, although I still have my own non-owners auto insurance since I rent outside of Zipcar for longer trips.
Potentially Wasted Time and Fines
The penalty is stiff if you don't return the car on time - a likely possibility given New York City traffic. Which leads to something else to watch for. Sometimes people don't return their cars on time, especially if they're returning during peak hours. I've noticed other renters waiting up to 1/2 an hour after their pickup allotted time. I myself inadvertently returned a car 20 minutes late after getting lost in the Bronx.
Inconveniences
Other minor faults. You can only make five advance full day weekend reservations. If you leave your stuff behind, it may be a hassle to to retrieve, since it's probable that someone is using the car right after you. I see people's forgotten belongings in the trunk all the time. Different garages have different policies. Some involve tickets you have to remember to keep, some are strict on getting a pickup time, some not. And some don't have enough manpower when everyone picks up their cars it once.
Most people would wonder, "Why would you need a car in NYC?" I don't - it's when I need to get *out* of NYC. Although there are commuter trains, during weekends, when you're most likely to leave the city and traffic is more manageable, it's just more convenient to drive, especially when you have lots to carry. And if you're driving with 3 or 4 people, it makes more economical sense. With zipcar, I find myself visiting my parents in the suburbs more often, able to get out anywhere quick for emergencies and I just feel more enabled, mobile.
Zipcar raised it's prices around April 2008, but it's not enough to radically change my driving habits. If the model, quality of service and pricing stays about the same, I will be using Zipcar for as long as I can afford gas. The big rental companies are starting to mimic Zipcar's hourly rental model and there might be future competitors to come, but Zipcar has a great head start, but I question their new strategy to rent to kids in colleges and universities. Hopefully, that won't lead to higher fees. Dude, don't crash that Zipcar!