Over the past few years, we've seen a number of startups offer ways for city-dwellers to give up their personal rides and make do with borrowing cars from time to time. Zipcar is perhaps the best example of that trend, functioning less as a rental service and more like a car co-op.

But recently, we've seen more drastic changes on the car-ownership front, facilitated by smartphones and the internet. We've written several times about car-sharing services that let owners rent out their vehicles to folks in need -- services like RelayRides, which yesterday inked a very impressive deal with General Motors and OnStar. Now, there's another car-sharing company on the block: Wheelz (not to be confused with Weeels, which is, of course, a cab-sharing startup). 

Like RelayRides, Wheelz lets a community of drivers share cars on an as-needed basis, without having to go through a lengthy reservation process. Wheelz installs a bit of hardware on participating vehicles, and renters use a smartphone or RFID card to interact with that hardware and drive away after they've made a quick reservation using the Wheelz app.

The difference between Wheelz and other car-sharing services is that Wheelz is restricted to college campuses. Like Zimride -- which began as a B2B solution to facilitate carpooling among employees and students -- Wheelz is bought by universities and made available to members of those communities. It's not open to the general public, even for folks who live or work near a participating college. In fact, it's not even available across networks -- so, for example, students at one university aren't able to borrow cars at another university.

Will it fly?

On the one hand, Wheelz just launched last week and has a lot of catching up to do. Not only is there the RelayRides/GM/OnStar partnership to contend with, but there's also Getaround, which recently scored $3.4 million from a range of investors and walked off with a $50,000 prize as winner of TechCrunch Disrupt NYC back in May. 

On the other hand, Wheelz is limited to closed communities. Because each Wheelz network is restricted to a particular college or university, Wheelz owners and borrowers are more likely to know one another than, say, Getaround participants. That's important because one of the biggest boogeymen haunting car-sharing services is the potential damage borrowers might inflict on owners' cars. But when the two parties know one another, chances are better that the borrower will respect the owner's property.

We still have a lot of doubts about Wheelz and its ilk. Like communism and libertarianism, car-sharing services look okay on paper, but they typically fall to pieces in real life because humans are so unpredictable and, well, human. For the curious, however, here's a brief overview video: