|The E320 BLUETEC. Click to enlarge.|
Mercedes-Benz upped the diesel ante in the US by announcing that it will introduce an E320 BLUETEC sedan to the US market in the Fall of this year. This would be the vehicle’s first introduction, worldwide. The company also announced a BLUETEC version of its just-introduced full-size SUV GL family—the VISION GL 320 BLUETEC—using the same powertrain and similar emissions control system.
The E320 BLUETEC will deliver about 35 mpg US (6.7 l/100km) and be“50-state ready” for emissions restrictions (given the availability of the EPA-mandated ultra low-sulfur diesel)—meeting, in other words, even the more stringent emissions standards of states such as California where new diesels currently are not sold.
The full-size SUV version will deliver about 26 mpg US (9.4l/100km)—the highest of any full-size SUV to-date, and possibly slightly better than GM expects to deliver with its upcoming twin-mode hybrid Tahoe full-size SUV. (That said, the GL BLUETEC is still officially a concept, with no firm release date.)
The Chrysler arm of DaimlerChrysler will make use of BLUETEC technology as well, and introduced at the Detroit show a concept BLUETEC Jeep Grand Cherokee that promises 25 mpg US. Dieter Zetsche, Head of the Mercedes Car Group and CEO of DaimlerChrysler since January 1st, who made the announcements, also said that the company will work on diesel hybrid implementations (some of which were announced at the Frankfurt IAA event last fall.)
Each of the US-bound BLUETEC vehicles announced uses a V6 diesel engine that develops 155 kW (211 hp) and 540 Nm of torque.
The emissions aftertreatment systems on each differ, however. DaimlerChrysler uses BLUETEC as a term to refer to a combination of technologies for passenger cars and light trucks to reduce all relevant emissions. Components will vary with the vehicle.
The E320 model uses an oxidizing catalytic converter, an advanced DeNOx catalytic converter, a particulate filter, and a Selective Catalytic Converter (SCR) in that sequence. The VISION GL uses a combined oxidizing catalytic converter and particulate filter, a urea-injection-based method for reducing oxides of nitrogen from the exhaust stream (AdBlue), and a catalytic converter. Diagrams of each emissions system are below. (More details on the specifics of each to follow in a subsequent post.)
|E320 BLUETEC Emissions System.||VISION GL320 BLUETEC Emissions System.|
|Click each diagram to enlarge.|
The oxidizing catalytic converters (diesel oxidation catalysts—DOC) oxidize CO (carbon monoxide) to CO2 (carbon dioxide) and HC (hydrocarbons) to H2O (water) and CO2.
The DeNOx catalytic converter and the urea-based AdBlue system in combination with the SCR catalytic converter tackle NOx reduction, and the self-regenerating particulate filter handles PM.
Mercedes-Benz’ strategy for developing its BLUETEC platforms includes the following:
Optimization of the engines and their combustion processes to minimize in-cylinder emissions. This includes electronic engine management, four valves per cylinder, third-generation common-rail direct injection with piezoelectric injectors, a turbocharger with variable nozzle turbine and exhaust gas recirculation (EGR).
Oxidizing catalytic converters to minimize emissions of carbon monoxide (CO) and unburned hydrocarbons (HC).
A particulate filter, fitted as standard in all Mercedes-Benz diesel cars in many countries since summer 2005, to reduce particulate emissions by as much as 98%, thus undercutting even the current EU 4 particulate limits (0.025 g/km). This technology also ensures compliance with the US limits currently in force.
The use of BLUETEC to cut oxides of nitrogen. The BLUETEC Selective Catalytic Reduction system reduces oxides of nitrogen by up to 80%, according to Mercedes. The decisive factor in ensuring that the catalytic converter works extremely efficiently is precise metering in line with the current engine operating state.
Mercedes-Benz has already deployed its BLUETEC technology in commercial vehicles with a GVW above six tonnes, with more than 10,000 so-equipped untis on the road. The BLUETEC trucks, according to Mercedes, already exceed the Euro 5 specifications coming in 2009.
The announcement of the E320 BLUETEC marks a more aggressive stance toward using diesels as a solution for increasing demands for fuel economy in the US. So far, however, that has encompassed only the larger vehicles. The application of BLUETEC in a Jeep, even in a concept, however, might mark the beginning of a broader diesel roll-out that would impact some of the smaller platforms, such as the new Caliber.