With a drag coefficient, or Cd value, of 0.32, the new Mercedes-Benz M-Class (ML 250 BlueTEC) also sets a new best figure for this vehicle class (total aerodynamic drag Cd x A = 0.92, predecessor 0.94). Painstaking simulations undertaken with the digital prototype, along with final touches added in the wind tunnel, ensure a perfect flow of air around the vehicle. The key factor determining the low wind resistance is the aerodynamic efficiency of the basic bodyshell, including the optimised design of the front bumper with its integrated spoiler, of the A‑pillars and of the roof spoiler, plus numerous other detailed improvements.

These include:

Sealing around the radiator section with adjustable fan shutter
Sealed joints between the bonnet and the headlamps
Front wheel spoilers
Air outlets in the front wheel well liners
Redesigned exterior mirror housings
Optimised roof spoiler
Side spoilers on the rear window (ML 250 BlueTEC 4MATIC)
Underfloor and engine compartment panelling
Aerodynamically optimised light-alloy wheels for the diesel models

Detailed analysis: "energy-transparent vehicle" creates transparency

The "energy-transparent vehicle" development tool, created in-house by Mercedes-Benz, was piloted as part of the M-Class development process. The outstanding opportunities presented by this method, which can detect the possibilities for optimisation in even the most minute component, will be exploited on all new model series in the future. An exact and meticulous examination of the flow of energy throughout the vehicle (tank to wheel) helps the development engineers to optimise every single assembly that has an impact on fuel consumption, right down to individual components, such as wheel bearings.

The idea for the "energy-transparent vehicle" stemmed from the failure in the past to verify or demonstrate clearly the many factors affecting consumption and the interaction between fuel-saving measures. Using the "energy-transparent vehicle" tool, the engineers can now detect detailed potential optimisation measures by breaking down energy flows into cause and effect and analysing energy interactions within the entire vehicle.

The process draws on complex, highly precise metrology which records some 300 energy-relevant measurement points with a sampling rate of up to 1000 measured values per second. Every minute some 2.4 million measured values are generated, which can subsequently be analysed to reliably pinpoint optimisation potential. The process is complemented by energy simulation models which are validated by means of the measured variables. This enables the energy efficiency of individual major assemblies and components as well as the entire vehicle to be analysed and quantified.

Once the specialists have identified a vehicle component with energy shortcomings, they team up with the relevant specialist departments to devise solutions. This cooperation focuses on design, or the properties of the materials used in individual vehicle components such as wheel or axle bearings. In addition, modified control strategies can also produce the desired outcome.

The "energy-transparent vehicle" process which is exclusive to Daimler enables the development engineers to highlight and leverage optimisation potential both for cars with conventional internal combustion engines as well as hybrid, electric or fuel-cell drives. In future, this process may even give rise to a generally applicable development tool for all machines and help boost energy efficiency across the board. A wide range of applications are conceivable. Whether in industry for power stations, (wind) generators, pumps or conveyor systems, in the home for refrigerators, washing machines, dryers and lawnmowers, or for transportation applications involving ships, trains or planes - the optimisation potential of disparate technologies to save energy could be analysed in detail with the consistent usage of this technique and implementation recommendations made.