“We look at the vehicle as a complete system, and thus analyze the components, systems, and phenomena associated with it.” Raimund Siegert has the cross-functional task of analyzing full vehicles with regard to their resource efficiency. He carries out this complex task with the help of state-of-the-art simulation technology that enables him to view the various ways in which individual vehicle components and systems influence and react with one another. Ideally, the process will result in a “downsized” vehicle with less displacement without sacrificing power output or comfort.

BlueEFFICIENCY: Greater efficiency through innovation and technology

“We need to look at the vehicle as a complete system,” says Raimund Siegert, who is responsible for Full Vehicle Energy Management Simulation Analysis at Mercedes-Benz Cars. Siegert’s department employs a network of investigating engineers who monitor all design areas in search of unnecessary energy losses or resistance to vehicular motion.

The engineers examine everything down to the smallest component, utilizing state-of-the-art simulation technologies that reveal potential for optimization. They also provide clues on tricks for reducing tire rolling resistance or identifying areas where soundproofing materials will have no effect and should therefore not be installed. “We analyze the components, systems, and phenomena associated with the vehicle,” is how Siegert describes his department’s holistic approach, the results of which can already be assessed on the basis of the new BlueEFFICIENCY models from Mercedes-Benz. Thanks to a complete package of optimization measures, fuel consumption in the already economical Mercedes-Benz C 180 KOMPRESSOR model, for example, has been reduced by 0.9 liters per 100 kilometers.

Such achievements, according to Siegert, “require us to permanently reevaluate what we do.” It’s also often the case that seemingly naive questions end up leading to new solutions. Power steering systems offer a good example here: Up until recently, the hydraulic pump in a vehicle with power steering would deliver the maximum pressure needed to support the driver as soon as the car was started. Then somebody began questioning the procedure. After all, the additional power is only needed when the driver actually steers the car; the supply of pressure in all other situations is a pure waste of energy. That’s why these days, an additional valve regulates pump pressure in accordance with the actual steering requirement. The result is reduced fuel consumption of 0.14 liters per 100 kilometers, whereby the system has no detrimental effect on comfort or safety. “Saving without any sacrifices” is therefore the motto of energy management at Mercedes-Benz.

The power steering example also illustrates how a single improvement often leads to a whole range of further optimizations. “Energy losses are like sources of noise,” says Siegert, who speaks from experience. “As soon as you get rid of one, you start noticing two others.” After implementing the steering pump control, engineers therefore suddenly started asking themselves why they couldn’t do the same thing with the fuel pump. This might all sound easy, but in reality it’s rather complicated, as altering one part of a complex system – which is exactly what today’s automobiles are – frequently results in unintentional effects in another area. It’s kind of like a big bowl of spaghetti: When you pull on one end, you’re often surprised to see where the spaghetti on the other end starts to move.

Returning to the automotive realm, control systems require a continually reliable source of electricity – and increasing the number of control systems places greater demands on both the vehicle’s power network and its battery. Here, sufficient capacity must be ensured for those rare instances when all control systems simultaneously demand maximum power. The big question here is, how long can such a situation last? The answer can be obtained from an extensive database that stores information on trips taken every day by thousands of customers. If the analysis of the data shows, for example, that such a power surge never lasts longer than a minute, even in rare situations, the system can be designed accordingly. “The results are taken into account in development,” says Siegert.

“We take a close look at the way our customers use their vehicles because that’s the only way to ensure that our optimization measures will be truly effective in practice,” he says. For example, lowering the drag of the C-Class appears at first glance to result only in a modest 0.07-liter reduction in fuel consumption. That’s because the standardized driving cycle test is based on an average speed of only 33 km/h (21 mph). “We, however, know that our customers travel at an average speed of just over 50 km/h (31 mph) in the annual mean – and in such real-life conditions, the fuel savings achieved by the aerodynamic optimization package total 0.15 liters,” Siegert explains.