ECOdiesel Review - Popular Science

Volkswagen is claiming to make the cleanest production diesel in the world with its new Jetta GL ECOdiesel. That's still not clean enough for future California emissions standards, but it goes a long way toward eliminating the diesel engine's most obnoxious behavior -- the smelly black particles characteristic of most diesel exhaust.

Environmentally, diesels have several advantages over gasoline. They are inherently lean-burn engines, consuming profuse quantities of air to burn fuel, which tends to reduce the production of carbon dioxide, the primary gas contributing to global warning.

VW takes this lean burn advantage a step further in the ECOdiesel, using a low-pressure turbocharger as an air pump to improve combustion efficiency. The low-boost turbocharger reduces the formation of carbon particulates -- the highly visible diesel soot.

VW then adds an oxidation catalyst to burn aromatic hydrocarbons, the exhaust-gas component the produces the characteristic diesel smell. It is one of the few efforts to put an oxidation catalyst on a production car, not to be confused with the short-lived particulate traps that so far have not been perfected.

The ECOdiesel produces 59 horsepower, a marginal increase from the existing 52-hp VW diesel Jetta but an interesting efficiency gain from what is mainly an emissions control program.

The performance that results is still best described as stately, although VW has long mastered the art of building small, free-revving diesels that lack nothing in throttle response, and the ECOdiesel is pleasantly agile, if not a track-burner.