BMW is set to re-introduce diesel power to their US product lineup, with the North American debut of two vehicles at the 2008 North American International Auto Show (NAIAS) in Detroit. They will debut two vehicle models equipped with the BMW Advanced Diesel with BluePerformance: the X5 xDrive35d and the 335d. These models utilize BMW’s 3.0-liter inline-six featuring Variable Twin Turbo Technology and will be available for sale this autumn in all 50 states.
The 335d can reach 62 mph in 6.2 seconds and is rated 265 HP, with 425 lb-ft maximum torque, and has an estimated fuel economy rating of 23/33 MPG, which compares favorably to the 19/28 rating of the 328i and the 17/26 rating of the 335i. The BMW X5 xDrive35d accelerates from 0–62 mph in just 7.2 seconds and offers average fuel economy of at least 19/25 mpg (city/highway, provisional data). That is a major improvement over the X5 3.0 which is rated 15/21 city/highway. Perhaps those fuel economy figures will help reduce BMW’s CAFE annual fines.
BMW press materials state that their diesel engines have helped to significantly eliminate “any reservations regarding the acoustic properties of a diesel engine,” implying that their diesels are smoother and quieter than the diesel powerplants you remember from Volkswagens of the 1980s. Still, that is the stereotypical American consumer’s viewpoint of diesel engines. According to BMW, no less than 67 percent of all new BMWs delivered to customers in Europe are powered by a diesel engine. I think it is safe to say that a significantly smaller percentage of BMWs sold stateside will be diesel-powered.
BMW last sold a diesel in the United States in the 1980s: the 115 HP 524td, which was known as the fastest diesel of its time. Fortunately, times have changed. BMW’s current worldwide engine range comprises seven diesel engines: three four-cylinder models, three six-cylinder models and a V8. Both the six- and four-cylinder engines have aluminum crankcases helping to significantly reduce the weight of these engines. The 3.0-liter inline-six mill being indroduced in these US-bound vehicles employs Variable Twin Turbo Technology, in which a small turbocharger first cuts in at low engine speeds. Thanks to its low inertia, this turbocharger develops boost in response to even the smallest movement to the gas pedal and without the slightest delay. As engine speed increases, the second, larger turbocharger cuts in, developing maximum torque of 425 lb-ft at just 1,750 rpm.
In addition to the above Variable Twin Turbo Technology, new technical highlights of BMW Advanced Diesel include an aluminum crankcase and third-generation common-rail direct fuel injection. To ensure full compliance with the demanding emission standards in California and other US states, BMW uses SCR technology to reduce nitric oxides (NOX), enabling nationwide introduction of BMW Advanced Diesel with BluePerformance as a 50-state model.
Similar in principle to other “blue” diesels sold in the USA, BMW’s Advanced Diesel with BluePerformance incorporates an oxidation catalyst placed just downstream of the exhaust manifold, a diesel particulates filter housed in the same unit and an SCR (selective catalytic reaction) catalyst with the urea injection. In addition to filtering out even the smallest particles from the flow of exhaust gases, this combination ensures effective reduction of nitric oxides (NOX) by way of a chemical reaction within the exhaust system initiated by the injection of a small dose of urea referred to as AdBlue. With a two-tank system for delivery of the AdBlue urea solution, it can be refilled at regular service
intervals. Since all BMWs sold in the US benefit from free servicing for four years or 50,000 miles, the vehicle’s driver won’t have to pay for refilling of the AdBlue solution until after that time.
The reason that BMW sells so many diesel vehicles in Europe is twofold: Diesel cars get better fuel economy (which matters in Europe where fuel is more expensive than it is here in the USA), and BMW’s diesels really are quite good. Whether many “typical” American BMW drivers are willing to drive diesel cars is hard to say. However, for drivers of contemporary Volkswagen diesels or even hybrid sedans, who choose those cars for their powertrain rather than their driving experience, the 335d would certainly be a step up to a nicer car and a more dynamic driving experience. While the 335d doesn’t have the fuel economy of a VW Passat or Jetta TDI, it does have good fuel economy for a car with 6-second 0-60 time, which certainly adds up to a lot more driving-enjoyment per gallon.
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