Cecil replies:

It works, let's start with that — "works" being defined as "the cars don't get trashed," as distinct from "makes money," a question on which the jury is still out. So I won't get too gushy. Nonetheless, one can't help admiring the ingenuity of the thing. Having discussed this question at length with the folks at Zipcar and I-GO, Zipcar's local competitor (Zipcar is a national company headquartered in Cambridge, MA; I-GO is a project of the Chicago not-for-profit Center for Neighborhood Technology), I'd say there are three factors involved: (1) high technology, (2) old-fashioned gruntwork, and (3) one of the oldest motivators in the books.

First the technology. No doubt you take this stuff for granted. The people who invented it want you to take it for granted, because that means it's so reliable you don't need to give it any thought. Still, it's worth a moment's review. The modern miracles that make car sharing possible include:

• Smart cards. You give the car-sharing company your personal details, such as your driver's license and credit card numbers. They give you a plastic card containing a microchip with an ID number. After you reserve a car, you present the card to a reader on the windshield. The reader recognizes the number and, assuming you've made a reservation, unlocks the door. The CTA's Chicago Card Plus works much the same way. In fact, I-GO and the CTA offer a combo card that works on both I-GO cars and transit. You use the card to pay the bus or train fare, then use it again to get into an I-GO car parked near your stop.

• GPS. Not to get all Big Brother-y about it, but thanks to GPS the car-sharing computer knows where the car is, and thanks to smart cards it knows you're in it. If you're looking for a promising vehicle to abscond with, this one won't be at the top of your list.

• On-board computers. A baby 'puter in the car keeps track of when the engine overheats or the oil runs low. Yes, I know just about all cars have these nowadays. What they don't have is the next item.

• Cell phone technology. If the car has a problem, it calls the home office. When the home office gets your reservation, it calls the car and says you're coming.

• Smart phones and the Internet. Yes, I realize I'm confusing my communications technologies here. We live in a confusing world. Fact is, you can reserve a Zipcar/I-GO vehicle using just about any medium short of telepathy, and I don't doubt there's some kid in Mumbai who's working on that. Say you're out with friends when the mood strikes to visit that new bistro across town. You whip out your smart phone, launch an app to find the nearest car-share car, reserve it, wait a minute till the instructions are transmitted to the vehicle from car-share central, and there you go. With Zipcar (and maybe with I-GO, but I didn't think to ask), you can even use your smart phone to make the car honk its horn if you can't spot it. People have gone to the moon with less elaborate technology.

But we're just getting started. Impressive as all the above is, it merely means the car-sharing service doesn't need to have somebody on hand when you pick up the car or bring it back. It doesn't take care of basic chores such as cleaning the car or getting the oil changed. For that car-sharing services rely on hired help just like every other business. This part of the job has its cool aspects. The maintenance people for both Zipcar and I-GO ride to the scene on bicycles, which they toss into the trunk if they need to bring the car to the shop. I-GO contracts out the cleaning to a minority-owned business that mostly does its work in the middle of the night, when the cars are idle, and both companies boast of their environmentally sensitive cleaning methods.

Now we get to the heart of your question. The car-sharing companies service the vehicles periodically, or when they know something needs fixing. They don't inspect the cars after every use, as a car rental company does. Instead, they rely on the users not to mess the cars up, and to keep them filled with gas. (Both Zipcar and I-GO provide their vehicles with a limited-use credit card for this purpose.) For the most part, I'm told, people cooperate — not because they're necessarily virtuous, but because of that ancient motivator: peer pressure.

 The thing is, when you sign up for a car sharing service, you really are sharing cars. Although members can reserve any car they want, in practice they tend to use the same vehicles repeatedly. Since you've got a relatively small number of people driving a handful of cars, anyone with conspicuously bad habits stands out. Members are told to inspect the cars before using them and report damage and other problems lest they be held responsible. If you smoke in the car or your mutt gets dog hair all over it, you soon get found out and fined, and if you're really an incorrigible pig you get bounced. Car sharers are surprisingly diverse — I-GO CEO Sharon Feigon says when her organization throws its annual party for members, "all of Chicago shows up," with the fifty-something crowd as much in evidence as college kids. So you'd better not mess up the car, for fear of ticking off your (or somebody's) mom.

In short, at the most basic level, car sharing works. Whether it's a viable business, or an effective way to reduce auto dependence and save the planet, remains to be seen. Zipcar, a $130 million company with 325,000 members, hopes to make its first quarterly profit this year. Feigon observes that car sharing is a low margin venture — not-for-profit I-GO covers its operating expenses, but relies on government grants to expand.

No question, car sharing has its advantages from both a personal and big-picture point of view. Jonathan Gonsky, Zipcar's Chicago general manager, says each of its vehicles takes 15-20 cars off the road, and that its members typically save $600 a month on transportation costs, partly because they drive less and walk, bike, or take transit more. Feigon says I-GO surveys have found close to half of members either sell their personal cars or hold off on purchasing another one. I-GO's 14,000 members share just 250 vehicles, using them an average of 7-8 hours a day. (Zipcar owns 400 vehicles in Chicago but won't disclose local membership or usage statistics.) Both companies make extensive use of hybrids and other energy-efficient vehicles. (Zipcar also offers some luxury cars.) Two of of I-GO's car are plug-in electrics, and plans are in the works to install solar canopies that will charge electric car batteries. (My comment after a sun-free October: good luck with that.)

Car sharing is an interesting experiment — an urban approach to car usage, dependent on density and mass transit. Just do your bit and keep the muffin crumbs off the seat.

— Cecil Adams
Photo by Pat O'Neil