Natural-Gas Car Coming
   American Honda Motor plans to become the first automaker to mass market a vehicle that runs on natural gas. The Civic GX will go on sale to the general public during the second half of 2004. It will sell for about $20,000, about $3,000 more than a gasoline-powered Civic. The GX will cost about one-third less to operate than a car that runs on gasoline and will be much better for the environment, a Honda spokesman said. It will have a driving range of about 200 miles, about half of a regular Civic.