Instead, the new, cleaner engines have become a point of pride.

Indeed, thanks to cleaner engines, cars are no longer central to realistic strategies for dealing with smog.

And starting in 2007, new buses and trucks will be built with cleaner engines, he said.

His work is widely used in the automotive industry in the design of efficient and clean engines.

"Environmental factors are a bigger part of the buyer decision" now than they were when Honda began manufacturing its clean engines in 1974, he said.

In many cases cost is the only reason for which we do not have cleaner engines already.

This increase in miles negates the profit gained from using an economical and clean engine.

We need more than just cleaner engines and sulphur-free fuel.

How could we build vehicles with a "clean' engine which would have to operate using pollutant fuel?

London low emission zone introduced between 2008 and 2012 for commercial vehicles with older or less clean engines.