(FORTUNE Magazine) – Six bright-yellow taxicabs powered by compressed natural gas are now bouncing through the potholes of New York City, the newest contestants in the great race to create alternative-fuel vehicles. The best technology will dominate the urban fleets of the future. The race is by definition a clean one, as vehicles must meet tough new air- quality standards effective later in the decade. And they must burn domestically produced fuels -- other than gasoline -- to reduce the nation's dependence on foreign petroleum. Methanol, ethanol, and electricity are alternative alternatives, but natural gas vehicles, or NGVs, are off to a jack-rabbit start. More than 30,000 NGVs are already working in the U.S., mostly trucks operated by large fleet owners such as the U.S. Postal Service, United Parcel Service, Brooklyn Union Gas Co., and Consolidated Natural Gas of Pittsburgh. The trucks top off at more than 600 fueling stations now operating. New technology allows refueling similar to that of gasoline. Natural gas generally costs an equivalent 70 cents to 80 cents a gallon compared with gasoline, recently around $1.20. Boosters say NGVs produce 90% less of the pollutants that make smog-causing ozone.

The Gotham cabs, among the first of their kind, are fueled by Consolidated Edison Co., a sponsor of the test with Irene Leasing Inc., a Brooklyn cab company. Drivers have logged more than 60,000 miles on some cabs since December. How do the NGV hacks handle? Says one taxi dispatcher: ''You couldn't know the difference with your eyes closed.'' Isn't that how cabbies drive anyway?