Concept car : AirPod

The AirPod is a three-seat and three-wheel car that runs on compressed air.

(Credit: CNET)

Among the plethora of alternative fuels being put forth to replace oil, the most odd might seem simple: air. But MDI International, based in Luxembourg, showed off a car at the 2009 Geneva auto show that runs on just that. What motivates the little AirPod concept is the energy from compressed air stored in a tank at 5,000 pounds per square inch (PSI).

The driver sits alone in the AirPod, turning the front wheel with a joystick.

(Credit: CNET)

The AirPod vehicle is small, holding just three passengers, with a single seat facing front for the driver and a bench facing backward for two more people. MDI claims a range of more than 112 miles in an urban setting, and less than two minutes to refill the 46-gallon air tank. But even though the AirPod can reach speeds of just less than 45 mph, the air-powered engine produces only 8 horsepower, suggesting slow acceleration.

Because of the low horsepower, the AirPod is designed to be exceptionally light, coming in at 485 pounds. Because the air tank and engine don't take up much room, most of the AirPod is devoted to passenger space. The car is a three-wheeler, and the driver uses a joystick to turn, rather than a conventional steering wheel.

Although air power means the AirPod drives emission-free, some energy is required to compress air into its tank. MDI puts the cost of a tank refill at just 1 euro.

MDI has announced deals with Air France and KLM to run a test fleet of the AirPod cars at Charles De Gaulle airport in Paris and Schipol airport in Amsterdam.

See more Geneva auto show 2009.