Want to rent out your car when you're not using it? It just got a lot easier for GM car owners.

Car sharing isn't new, but what if it was your car that was being shared? A new crop of peer-to-peer hourly car rental companies are popping up--can they gain traction?

Using strangers for rides has yet to catch on in most places, but a bad economy and high gas prices can make almost anything palatable. Here are four startups that could start the ridesharing revolution.

The rental car agencies new car sharing business hits Zipcar where it hurts: cheaper prices and electric cars.

Zen Car will bring 29 vehicles into circulation, edging out a larger effort that will be unveiled in Paris in the fall.

Is Zipcar too pedestrian for you? Check out BMW on Demand, an hourly car-sharing program launching in Munich.