Thanks to the highly effective exhaust treatment system developed by Mercedes-Benz, BlueTEC vehicles fulfill the strictest global emissions standards to make them the cleanest diesels in the world. With the E 250 BlueTEC concept, which was created specifically for the North American market, Mercedes-Benz is now demonstrating how BlueTEC technology in the E-Class can be combined with a four-cylinder engine with optimized fuel consumption. When fitted to the 7G-TRONIC seven-speed automatic transmission, the E 250 BlueTEC boasts fuel economy of 28 mpg U.S. in city traffic and 39 mpg U.S.on the motorway (U.S. FE standards). The E 250 BlueTEC concept fulfills the strictest emissions standards, including Bin 5 in the U.S., and would even meet the considerably toughened limits laid down in EU6 legislation not due for implementation until 1 September 2014.

For the E 250 BlueTEC, the modern 2.2 litre four-cylinder CDI engine underwent a detailed redevelopment program in order to reduce further the internal raw emissions generated by the engine and to fulfil the legislative requirements for on-board diagnostics (OBD), as well as other factors. The power unit hardware incorporates features from the series production engines, such as four-valve technology, fourth-generation common-rail piezo direct injection, 2-stage turbocharger and exhaust gas recirculation. A highly sensitive electronic engine control system reacts precisely across the full range of operating conditions to optimise the combustion process. The exhaust gas treatment system incorporates an oxidation catalytic converter mounted close to the engine, as well as a diesel particulate filter, which is located at the rear bulkhead in order to shorten its regeneration time.

At the heart of the BlueTEC system are two SCR catalytic converters (Selective Catalytic Reduction) with an “AdBlue®” injector positioned upstream. “AdBlue®” is a synthetic, aqueous urea solution that enables the nitrogen oxide (NOx) to be converted into harmless nitrogen gas in the SCR catalytic converters.

The monitoring and diagnosis of the sophisticated exhaust gas treatment process is handled by several sensors, including a differential pressure sensor, a Lambda probe plus NOx and temperature sensors.

For on-board storage of the “AdBlue®” solution, the E 250 BlueTEC has a 25 litre tank equipped with a membrane pump, valve, pressure and temperature sensors and an electrical heating unit, which prevents the 33-percent urea solution from freezing at extremely low temperatures. The tank volume is sufficient for the duration of a full service interval and is refilled as part of the regular maintenance schedule. The “AdBlue®” tank is integrated into the spare wheel well in the boot.

E 250 BlueTEC combines environmental awareness, driving fun and comfort

The combination of the powerful four-cylinder engine with SCR technology makes a convincing argument not only in terms of fuel economy and emissions, but also with impressive performance and the associated fun factor. Thanks to a pair of Lanchester balancing shafts, the concept vehicle’s powertrain boasts the exceptionally smooth characteristics expected of a Mercedes-Benz.