Tread lightly takes on a whole new meaning
“Tread Lightly” is a maxim among environmentally-conscious off-roaders who love to explore the back country while leaving its natural beauty as untouched by their passage as possible. But when your conveyance is a Jeep Grand Cherokee equipped with a 5.7-liter Hemi V8 that’s getting barely 10-mpg while you idle over hill and down dale in 4WD-Lo, the SUV’s prodigious fuel consumption makes you out to be a hypocrite. Jeep, which is part of global automaker DaimlerChrysler, has a solution to this dilemma called Bluetec, and tucked a Jeep Grand Cherokee Bluetec Concept vehicle into the shadows of the 2006 North American International Auto Show. Before you get excited, there’s a catch. Bluetec is attached to a turbocharged, six-cylinder diesel engine, and most folks think of diesels as dirty, underpowered, and overpriced pieces of equipment. This is, however, a new kind of diesel. With the advent of common-rail direct fuel injection and four-valve cylinder heads in 1997, much of the clatter and smoke of older diesels was replaced with cleaner exhaust, more refined operation, and boosted power and torque ratings. Despite this upgrade, however, diesel engines have been unable to pass the most recent emissions regulations in the Northeastern U.S. and California. Bluetec technology, developed by DaimlerChrysler’s Mercedes-Benz luxury division, allows diesel-powered products to be sold in those regions starting in the fall of 2006, and will meet the most stringent regulations worldwide through the end of the decade. Editor’s Note: If you want to know how Bluetec technology makes a turbodiesel engine clean, read on. Otherwise, you’ll get bored, so skip to the end. Diesel fuel sold in the United States contains large amounts of sulfur, and this sulfur content, among other factors, is what causes a diesel engine to run dirty with nitrous-oxide emissions. With Bluetec technology, emissions are reduced through the use of an oxidizing catalytic converter, a particulate filter, and what Mercedes calls a DeNOx nitrogen-oxide reducing system. DeNOx is the key here, a storage catalytic converter designed to treat engine exhaust gases before they are emitted from the tailpipe, and it reduces nitrogen-oxides by up to 80 percent. A reducing agent called AdBlue is injected into the gases contained in the storage catalytic converter, releasing ammonia which converts the nitrogen oxides into harmless nitrogen. The separate tank that stores the AdBlue is refilled whenever the car returns to the dealer for service. To work properly, Bluetec technology requires the use of low-sulfur diesel fuel, defined as that with a sulfur content below 15 parts per million. This type of fuel will be available in the U.S. starting in the fall of 2006, but may not be widely available. Over time, however, the fuel will become the standard in North America, and DaimlerChrysler will be ready to capitalize on this with a fleet of Bluetec-equipped cars and SUVs wearing Chrysler, Dodge, Jeep, and Mercedes-Benz nameplates. Bluetec arrives first under the hood of the 2007 Mercedes E-Class, but will be added to three Benz SUVs and the Jeep Grand Cherokee shortly thereafter. In the Jeep, DaimlerChrysler theorizes that the Grand Cherokee Bluetec could achieve a highway fuel economy rating of 25 mpg, allowing the driver to tread lightly with the land and the Jeep to tread lightly with the atmosphere. And in the future, DaimlerChrysler plans to connect Bluetec diesels to hybrid drive systems to create even cleaner, greener, and more efficient vehicles. Clearly, DaimlerChrysler thinks that diesel will power tomorrow’s cars in greater numbers, and Bluetec will be the instrument it uses to ensure success.
Photos courtesy of DaimlerChrysler