50 MPG+ And Cleaner Than Gasoline: Where Are The 'Clean-Diesels'?

Since last year, many of us have been eagerly awaiting the introduction of ‘clean-diesels’: the 2008-2009 models touted as having superior mileage and cleaner emissions than comparable gas models.

So where are they? Strangely, promised 2008 models didn’t materialize, and I had trouble finding more on the story. As far as I can tell, we’ll just have to look forward to next summer’s release of the 2009 VW Jetta TDI. The new Jetta gets similar mileage to older models, 50 mpg ( though VW engineers claim 30% better mileage under real world conditions). More importantly though, it’s the first diesel to meet the world’s toughest emissions standards, California’s Tier II, bin 5, earning it clean-diesel status. If you noticed the recent lack of diesel vehicles for sale (especially in CA), it was the direct result of reengineering emissions systems:

Although it won’t be wearing the “BlueTec” badge, the Jetta will be using emission-cleansing technologies developed under the cooperative formed by Audi, Mercedes-Benz and Volkswagen to make it 50-state legal. Most BlueTec vehicles control NOx emissions—one of the biggest environmental hurdles facing diesels, along with particulate matter—by injecting a urea-based solution into the exhaust system upstream from the catalytic converter, where NOx is then converted into nitrogen and water. The Jetta will instead use a NOx-storage catalyst, which is basically a reservoir that temporarily holds the noxious emissions, like a particulate filter, until they can be burned off during one of the engine cycles.

These new advances reduce NOx emissions by up to 90%—good news for biodiesel advocates and anyone breathing air. 50 MPG on 100% biodiesel has a nice ring to it, especially when the NOx-Biodiesel problem has been significantly mitigated. While we’d all like to say goodbye to old, dirty diesels, their inherent longevity means we’ll be stuck with them for some time. But those in the market for the latest model car might consider buying a state-of-the-art clean-diesel.

“…today’s clean-diesel engines are as clean as gasoline-powered engines,” says Chrysler’s Altermatt. “The standards have really improved, and that’s partly due to the input from the government, in terms of implementing stricter emissions standards…And in addition to now meeting those higher standards, these engines often provide the customer with engine performance that is the equivalent of gas engines, and sometimes better. And in many cases, the vehicles powered by diesel engines are more fun to drive, because they have better low-end response.

“So we do have some work to do in terms of changing old perceptions about diesels,” he said. “But the more of these that come into the market, the easier it will be to help people realize that diesel is now a very clean, viable alternative to regular gasoline.”

I hope that realization comes quickly, because we’re still years behind Europe. Just just take a look at the VW Polo: a 5-speed, 1.4 liter, sub-$20,000 hatchback that gets 60-70 mpg. When will we see these at home? My money is on 2010, when Honda expects to release a 62.8 mpg diesel in the U.S.

Green Car Congress (Nov. 16, 2007): VW Shows New Jetta TDI Clean Diesel at LA Auto Show

Popuar Mechanics (Dec. 4, 2007): 2009 Volkswagen Jetta TDi Test Drive: Clean Diesel’s 50 MPG Meets Prius-Humbling Thrust

CNN (Dec. 12, 2007): Diesels aren’t dirty anymore.

Popular Mechanics (July 31, 2007): Volkswagen’s Clean-Diesel, 70-mpg Polo May Head Stateside: Test Drive

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