In addition to extensive test bench trials, the new OM 651 engine generation in the Sprinter absolved around five million kilometres of endurance trials before it was cleared for series production. The low level of untreated emissions is the basis for the environmental friendliness of the new diesel engine generation. A compact dual-plunger injection pump generates the necessary pressure in the rail, while a throttle valve regulates the charge level. Other technical highlights include four overhead camshafts driven by a duplex chain and common-rail injection with piezo-electric injectors and eight-hole nozzles. This improves thermal management of the injection system and makes it unnecessary to cool the fuel. The continuously reduced friction and the interaction between the Mercedes-Benz engine oil and your vehicle's sophisticated exhaust gas aftertreatment systems can make the best use of your engine's potential while at the same time reduce fuel costs and pollutant emissions. At low engine speeds only the compact high-pressure unit is active, which means that a high charge pressure can already be built up at very low engine speeds. Test drives under low loads in distribution operations were no less demanding. The optimised airflow distribution is also remarkable.
In addition to optimised combustion, this is in part due to an increased exhaust gas recirculation (EGR) rate. The Sprinter is able to dispense with the SCR technology and addition of AdBlue used for trucks. In addition to a high output and low emissions, the sum of all these measures produces outstanding responsiveness, and therefore great agility and driveability. Maximum torque is already available at very low engine speeds, and is maintained over a wide rpm range. Diesel passenger vans are rated at a maximum of 2,862 lbs of payload due to a softer suspension setup and a GVWR of 9,480 lbs. To reduce weight, the intake air throttle is of plastic for the first time in a diesel engine. This not only saves time and money but also reduces the number of potential sources of error. As a welcome side-effect the engine warms up more quickly, which reduces wear and fuel consumption.
The required pump output has been considerably reduced as one of several measures designed to lower fuel consumption. This independently and adaptively controls its delivery volume, requires less power to drive and therefore lowers fuel consumption markedly. This is not only of decisive importance for the rated output and torque, but also for power delivery and therefore responsiveness. At 56 kW (76 hp) per litre, the most powerful version of the four-cylinder unit (120 kW/163 hp) has the highest specific output of any van engine in this class. In the other output versions of the four-cylinder engine, a further development of the two-stage turbocharging installed in a van for the first time in the preceding model is used. The new four-cylinder engines feature Lanchester balancers: two counter-rotating shafts lend these engines a level of smoothness never before achieved in this class. This ensures a high level of efficiency and rapid response.
Thanks to the very high level of engine efficiency, the Mercedes-Benz Sprinter is able to achieve both Euro 5 and EEV with exhaust gas recirculation. The previous engines remain available for markets which are not introducing Euro 5 for vehicles above 3.5 t gross vehicle weight in the autumn. As a logical next step, Mercedes-Benz is presenting the new OM 651 as the first van diesel engine to meet the Euro 5 emission standard. The driver does not notice the switchover from one to two-stage operation and vice versa, and the engine characteristics correspond to those of a large-displacement diesel engine. In fact one third of these endurance kilometres were accounted for by customer vehicles in practical operations. Available as an option, it presents drivers with the choice of two distinct set-ups, a more comfort-oriented response or a more sporty and firm one. Launched in 2002, the W211 E-Class was another evolution of the previous model and was considered by the motoring media as a more competitive offering to the long-term rival BMW 5-Series (which previously was the preferred choice of the motoring media).
