Under the microscope: Driving more efficiently: Intelligent co-pilots

It's not just the technology that's decisive: those who drive in an anticipatory manner save fuel and reduce CO2 emissions. In Mercedes-Benz vehicles intelligent assistants support the driver. And traditional tips for saving on consumption such as the correct air pressure in the tyres and not carrying any unnecessary weight on board still hold true.

From a technical perspective, Mercedes-Benz is permanently working on making vehicles more efficient and cutting their consumption. Consequently, the fleet consumption of Mercedes-Benz models has been cut by almost 50% since 1995. Yet, alongside technological parameters such as a more efficient powertrain and good aerodynamics, the person behind the wheel also has a great influence on consumption. This can be cut by up to 30 percent thanks to an energy-efficient driving style.

In many Mercedes-Benz vehicles with petrol or diesel engines, the animated ECO display in the multifunction display helps with this. It motivates drivers to adopt a fuel-saving driving style with differentiated evaluations of the driving style during the "Acceleration", "Cruising" and "Coasting" driving phases.

If drivers make an effort to drive smoothly, if they accelerate more moderately and let the vehicle coast, green bars will shoot upwards in the display and indicate an increased energy efficiency. In contrast, severe acceleration, fluctuating speeds and frequent braking will have a negative effect. Drivers can identify from the displayed percentage how much of the savings potential they have made use of so far.

ECO Assist: connected driving strategy for intelligent efficiency

ECO Assist coaches the driver in even more detail - by prompting the driver when it is appropriate to come off the accelerator, e.g. because the vehicle is approaching a speed limit, and by functions such as coasting and specific control of recuperation. For this purpose, navigation data, traffic sign recognition and information from the intelligent safety assistants (radar and stereo camera) are linked and processed.

ECO Assist takes the following traffic situations and information into account in its driving recommendations and efficiency strategy:

  • Route profile (bends, junctions, roundabouts, gradients)
  • Speed limits
  • Distance from vehicles ahead.

ECO Assist continuously generates coasting simulations in the background: depending on the state of charge of the battery and the traffic situation, it computes whether the vehicle should ideally be allowed to coast with the lowest possible driving resistance with the driver's foot off the pedals, or whether it should be decelerated so that the battery can be efficiently charged (recuperation).

Within the limits of the system, ECO Assist controls the overrun mode according to the situation as soon as the driver takes their foot off the accelerator. The driver is also given a visual prompt to do this: by the appearance of a "release accelerator" symbol in the central display (or if installed, in the Head-up Display). At the same time, a diagram gives the driver the reason for the recommendation (e.g. "Junction ahead" or "Gradient ahead").

ECO Assist predictively computes the driving situation when deciding whether to drive with the lowest resistance or whether to recuperate. Examples include dips, brows or speed limits ahead, which the system recognises from the map data.

  • Dip: The vehicle recognises that a downhill gradient is followed by a climb, and that a speed limit is shown. The driver receives the prompt "Foot off accelerator" in good time. As soon as the driver acts on this, the vehicle continues with the drive switched off. Recuperation takes place on the downhill stretch, but only enough to ensure that the maximum permitted speed is maintained. Recuperation ends just before the lowest point in the dip, and coasting commences to maintain as much impetus as possible for the uphill stretch in the interests of energy efficiency.
  • Brow: If ECO Assist recognises that "coasting" makes sense on account of the individual driving situation, the topography and the speed limits, the driver is told to "remove foot from accelerator" even before reaching the brow. The vehicle then drives in "coasting" mode over the brow and subsequently uses the slope to reach the target speed.
  • Speed limit: When the system recognises a speed limit from the navigation data or via Traffic Sign Assist, the driver is once again prompted with "Foot off accelerator pedal". The vehicle is then gently decelerated (while recuperating) to the new speed, followed by coasting. In this way suitable speeds for junctions, roundabouts and bends are also supported.
  • Slow-moving traffic: When the radar sensors of the system recognise slow-moving vehicles ahead while coasting, coasting is automatically interrupted if necessary. Deceleration with recuperation takes place to the extent that braking action by the driver is often unnecessary. If the vehicle ahead accelerates, coasting is reactivated automatically so as to cease deceleration and maintain the current speed as much as possible. The driver operates the accelerator if needed.

Hybrid and electric vehicles also in part have a haptic accelerator. This generally helps the driver to achieve an economical and comfortable driving style. A pressure point in the pedal, for example, tells the driver that the maximum electric power is being delivered. If the driver continues to press the pedal beyond the pressure point, the combustion engine kicks in. A perceptible resistance in the haptic accelerator advises the driver to take their foot off the accelerator. If the driver follows this recommendation, the combustion engine is switched off and decoupled from the powertrain.

Another special feature of the hybrid models: To increase the driver's motivation to follow the recommendations of ECO Assist, the on-board computer records how many kilometres/for how much time during a journey the car was driven with the combustion engine off, and shows this in the central display. The reward not only takes the form of reduced fuel consumption, but also an increased electric range.

Traditional tips for saving on consumption : Avoid unnecessary loads

A host of physical figures, some of which can be influenced before and some during the journey, have an effect on consumption and/or range.

  • Drag Drag is minimised by the most favourable aerodynamics. Drag can be kept low if you do not have a roof rack or bicycle rack. And since drag increases with the square of speed, driving slower equals a lot of savings.
  • Roll resistance: Additional weight, e.g. luggage, as well as air pressure in the tyres that is too low increase roll resistance. This means that the energy requirement to accelerate the vehicle and to keep it at a constant speed increases.
  • Driving style: Driving in a high gear at low engine speeds and with engines generating plenty of torque will allow driving without having to shift gears too many times to enable a more cost-efficient driving style. In ECO mode, automatic transmissions change up gears earlier, supporting an economical driving style at lower engine speeds. Modern transmissions such as the 9G-TRONIC with a wide spread of gear ratios enable the engine speed to be reduced overall. Heavy braking and accelerating increase fuel consumption. Both can be avoided by anticipatory driving. In addition, it makes sense to use the start-stop function even for short idle times.
  • Mercedes-Benz Driving Events offer special Eco Training. The participants in this half-day event conduct consumption measuring drives and learn how to recognise and use savings potentials.
  • Comfort equipment: Auxiliary consumers such as the air conditioning system or seat heating also influence fuel consumption because in most models, the electricity required to run them is generated by the combustion engine.