Most people know that today’s passenger-car diesel engines are much cleaner than those of even a few years ago, but the surprising results from recent testing shows that the heavy-duty diesel engines in big trucks have made even more dramatic strides.
;Heavy trucks and buses could lose their image as stinky, soot-spewing monsters as the current fleet is replaced with today’s cleaner models. According to recently released data from the Advanced Collaborative Emissions Study, overseen by the Health Effect Institute, shows that the engines (from Caterpillar, Detroit Diesel, Volvo, and Cummins) had an overall average 90 percent reduction in exhaust pollutants from 2004 to 2007. Particulate matter—soot—was cut by 99 percent. Even smog-forming nitrous oxides, typically the most difficult to control of diesel exhaust emissions, were 70 percent lower.
Besides their beneficial effect on air quality, dramatically cleaner trucks and buses could also help change people’s perceptions about diesel engines in general, helping to create more widespread acceptance of diesel-powered passenger cars.