Comments on: Diesel Hybrids http://www.policywank.com/2007/06/01/diesel-hybrids/ Wankers Welcome Wed, 26 May 2010 20:29:36 +0000 hourly 1 http://wordpress.org/?v=3.2.1 By: Argent http://www.policywank.com/2007/06/01/diesel-hybrids/#comment-5521 Argent Sat, 09 Jun 2007 20:47:27 +0000 http://www.policywank.com/2007/06/01/diesel-hybrids/#comment-5521 Diesel represents a big controversy from an environmental standpoint. Diesels have lower specific fuel consumption than petrol engines and produce fewer unburnt hydrocarbons, CO, and CO2, but because of the nature of diesel combustion, which is inherently 'lean' and higher-temperature than gasoline engines, they have significantly higher NOx emissions. Euro emissions standards -- up until next year, I think -- have had separate tiers for petrol and diesel, although that's a matter of great controversy in the EU. It is possible to make diesels meet U.S. federal NOx standards, but it's expensive, requiring complex NOx catalysts. Such catalysts are also incompatible with the high sulfur content that U.S. gasoline has had (which also kept us from getting technologies like direct-injection). Low-sulfur fuels are now being phased in here, and so Mercedes is about to roll out its "Bluetech" diesels for the U.S. market. I think they will still not be available in states with California-style emissions, making them 44-state vehicles. Hybrid or not, I would buy a BMW 330d if I could. It has superb real-world performance (no top end, and a somewhat heavier nose, but boatloads of torque), and in the kind of driving I do, I would get around 30% better fuel economy than I do with the Mazda. (I generally get 25-28 mpg overall, topping 30 only in steady highway driving, whereas the 330d would drop below 30 only if I spent all my time on the drag strip.) Diesel represents a big controversy from an environmental standpoint. Diesels have lower specific fuel consumption than petrol engines and produce fewer unburnt hydrocarbons, CO, and CO2, but because of the nature of diesel combustion, which is inherently ‘lean’ and higher-temperature than gasoline engines, they have significantly higher NOx emissions. Euro emissions standards — up until next year, I think — have had separate tiers for petrol and diesel, although that’s a matter of great controversy in the EU. It is possible to make diesels meet U.S. federal NOx standards, but it’s expensive, requiring complex NOx catalysts. Such catalysts are also incompatible with the high sulfur content that U.S. gasoline has had (which also kept us from getting technologies like direct-injection). Low-sulfur fuels are now being phased in here, and so Mercedes is about to roll out its “Bluetech” diesels for the U.S. market. I think they will still not be available in states with California-style emissions, making them 44-state vehicles.

Hybrid or not, I would buy a BMW 330d if I could. It has superb real-world performance (no top end, and a somewhat heavier nose, but boatloads of torque), and in the kind of driving I do, I would get around 30% better fuel economy than I do with the Mazda. (I generally get 25-28 mpg overall, topping 30 only in steady highway driving, whereas the 330d would drop below 30 only if I spent all my time on the drag strip.)

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