Zip Cars are reducing the amount of rubber on the road and saving its riders a little green.

Here's how it works.

Cars are parked in various locations around town.

They're sitting there waiting for zip car members to jump in and go.

Zip car users reduce wear and tear on their own cars.

Most save about 4,000 miles a year.

That means less money spent on gas, oil and repairs.

Mass transit leaders say that helps everyone.

If you can share a car with your neighbor and it works, you could share insurance, gas, and other things, and the beauty of this is gas and insurance is built in to the cost of using the car.

Other benefits include less congestion and air pollution.

The Zip Car program is expanding to communities all over the U.S.