Engineers at Honda took this gloomy statistic as a challenge. They were understandably pleased with themselves when they unveiled their prototype, installed in a Civic, last November. At official inspection stations, tailpipe emissions would simply not register. It suppressed hydrocarbons, nitrous oxides, and carbon monoxide at least 60 times better than the 1997 federal limits for new cars. In fact, Honda's natural-gas Civic accomplished all this without sacrificing the benefits of good old internal combustion, such as more horsepower and longer driving range, or the lower cost of mass production.
Natural gas contains methane and burns more efficiently than gasoline.
And since methane contains less carbon than gasoline, it produces less carbon dioxide, a greenhouse gas. But Honda's persistence was also crucial to the project. The company had already managed to meet the strict ULEV standards with an experimental gasoline engine, so it had no practical need to make further improvements. Honda engineers nevertheless wanted to see how close they could get to a true zero-emissions car, and they decided to modify the gasoline engine to accept natural gas. Like a trick question on an engineering exam, the solution, it turns out, is to reject the whole premise.