'Green' machines at Tokyo show

TOCHIGI, Japan: Japanese carmakers have made the environment their number-one issue at the Tokyo motor show, with Honda Motor Co reasserting its old claim of world leadership in reducing tailpipe pollution.

On Monday, Honda unveiled a four-cylinder gasoline engine it said was so pollution-free that it could actually clean the air in smog-bound areas such as Los Angeles. It conceded, however, that the technology is complex, expensive, unproven and years away from the market.

Honda's stature in engine development, however, gives the claim credibility. In 1975, it was the first carmaker to produce an engine to meet U.S. clean-air standards, and it has remained among industry leaders in technology aimed at making gasoline engines more efficient.

It says its experimental Z-LEV -- zero level emission vehicle -- produces just a 10th of the emissions allowed under California's stringent ultralow standard. "This new engine is a practical approach and will be applied to mass-market Honda products in the near future," said Honda president, Nobuhiko Kawamoto.

The Z-LEV's emission control system is the first to use Honda's hybrid catalyst that traps hydrocarbons during the crucial one-minute phase of engine warmup and later releases them for cleaning. But there are hurdles, including lowering the cost of the hybrid catalyst and long-term durability.

Honda engineers say they hope to offer the Z-LEV, based on Honda's 2.3-liter, four-cylinder engine, for just US$2,000 more than today's ULEV engine-equipped vehicles available in California.