OK, maybe they haven't been perfected yet, I don't know, but here are some more links...
According to some sources, they have much better mileage than gasoline vehicles. (Air Cars can travel 200 kilometers for just 1.5 euros)
http://aircarfacts.com/
one of a handful of planned Air Car models, can hit 68 mph and has a range of 125 miles. It will take only a few minutes for the CityCAT to refuel at gas stations equipped with custom air compressor units; MDI says it should cost around $2 to fill the car’s carbon-fiber tanks with 340 liters of air at 4350 psi. Drivers also will be able to plug into the electrical grid and use the car’s built-in compressor to refill the tanks in about 4 hours.
http://www.popularmechanics.com/auto...s/4217016.html
achieves over 100 gas-equivalent mpg and over 90 mph, has zero to low C02 emissions,
http://zeropollutionmotors.us/