MB BlueEFFICIENCY - Lower Cd, lower weight, LRR tires - 12% improvement in FE

Discussion in 'Diesel powered automobiles' started by xcel, Feb 28, 2008.

  1. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    The Europeans are getting it, where are the Americans?

    [xfloat=left]http://www.cleanmpg.com/photos/data/501/2008_MB_C-Class_BlueEfficiency.jpg[/xfloat]Wayne Gerdes - CleanMPG - Feb. 28, 2008

    2008 Mercedes-Benz C-Class BlueEfficiency. Mercedes-Benz will be adding even more fuel efficient sedans to the C-Class Model lineup in Europe.

    Intelligent measures and technologies have been applied that enable a reduction in the fuel consumption of the C 180 gasoline and C 200 CDI turbo-diesel models of up to twelve percent, while retaining the high levels of comfort and safety typical of the newly redesigned Mercedes C-Class. The BlueEFFICIENCY version of the 136 hp C 200 CDI Turbo-diesel is rated at 46.1 mpgUS combined on the Euro test cycles corresponding to just 135 g/km of carbon dioxide.

    Mercedes has made significant improvements to address many major design obstacles to better fuel economy including total weight, aerodynamic drag, rolling resistance, gearing and the power steering efficiency of their recently redesigned C-Class. Together, these measures add up to a combined fuel saving on the New European Driving Cycle (NEDC) of 4 mpgUS for the C 200 CDI.


    The design improvements to the standard C-Class shaved an additional 55 lbs on average from vehicle weight. This achievement is due in part to a newly developed windscreen made of laminated glass, which weighs 2.5 lbs less than before. Between the panes of glass lies a new, acoustically effective plastic membrane which efficiently absorbs wind noise. This has enabled Mercedes engineers to reduce the thickness of the windscreen, achieving a further weight reduction without compromising aural comfort in any way.

    The noise-insulating lining of the firewall has also been weight-optimized with the help of special materials. Using computer simulations, Mercedes-Benz recalculated the required firewall insulation and precisely redefined the material thickness of the sound-absorbing resinous foam to correspond with measured noise input. This needs-driven redesign reduces the weight of the lining by around 20 percent.

    Forged lightweight wheels also have a positive effect on the weight. The wheels tip the scales at a full 4 lbs less per rim than the conventional light-alloy wheels, saving a total of more than 16 lbs per vehicle. These new lighter weight wheels have aerodynamic benefits too.

    Tire rolling resistance

    In addition to lightweight construction measures, Mercedes-Benz paid particular attention to reducing rolling resistance. In collaboration with Michelin, Mercedes engineers developed lightweight tires with a particularly low rolling resistance coefficient (RRc).

    Rolling resistance is primarily caused by tire deformation as the tire contacts the road surface. This has a braking affect on the car since additional energy is required to overcome the deformation resistance - therefore, the higher the rolling resistance, the higher the fuel consumption. Up to approximately 60 mph, rolling resistance has a greater effect on fuel consumption than aerodynamic drag.

    The belt of this newly developed tire contains a multi-layered mesh of high-strength steel for less deformation. It is also lighter in weight than the conventional design, enabling a further 3.5 lbs to be saved per set. The secret lies in the chemical composition: the rubber compound for the treads and side walls is designed to ensure that rolling resistance is reduced by 17 percent while preserving optimal handling and braking characteristics.

    Aerodynamic Drag

    At 70 + mph, aerodynamic drag of the vehicle accounts for approximately 50 percent of the dynamic resistance a passenger car must overcome.

    The Current C-Class sedan has a drag coefficient of 0.27 and is among the most aerodynamically efficient vehicles on the market. This is the result of a whole series of intelligent design decisions -- tail lights with ventilation slits reducing drag are among these features. They accomplish their purpose by influencing airflow along the side walls, causing it to break off at the tail lights without turbulence behind the vehicle. In this way the patented tail lights of the C-Class replace the usual spoiler lips.

    In the new BlueEFFICIENCY versions, Mercedes has succeeded in reducing even further the already low Cd figure with a number of other detailed measures:
    • Smooth underbody cladding ensures that air can flow beneath the vehicle body without turbulence.
    • Partially blanking off the radiator grille reduces the airflow into the engine compartment, thereby lowering wind resistance. Cooling of the four-cylinder engines is still adequate even with this modification.
    • Sealing joints between the hood and headlights as well as between the bumper and headlights improves airflow around the front end of the vehicle.
    • The housings of the exterior rear view mirrors were developed in a wind tunnel for a particularly streamlined form.
    • Lowering the vehicle by .6 inches reduced aerodynamic drag even further.
    • The design of the new lightweight wheels also meets aerodynamic requirements and improves the airflow around the vehicle flanks.
    With the above improvements, the BlueEFFICIENCY’s Cd figure has been reduced by another seven percent to an astonishing 0.25, representing a major contribution to improved fuel efficiency.

    Taller geared drivetrain plus power steering energy management

    The BlueEFFICIENCY C 200 CDI sedan is equipped with a newly developed final drive featuring further-improved anti-friction bearings, forged differential gears and a sophisticated lightweight construction. These measures reduce the friction forces within the transmission, improving drivetrain efficiency by removing parasitic drag.

    The standard and now taller final-drive ratios of the BlueEFFICIENCY were changed from 2.65:1 down to 2.47:1 helping reduce fuel consumption even further. The C 200 CDI model is equipped with a six-speed manual transmission. With the sixth gear ratio of 0.828:1, top gear considerably reduces the engine rev’s at a given speed thus improving fuel economy of the vehicle even further.

    Energy management of peripheral engine powered equipment is another key focus area. The BlueEFFICIENCY C-Class models use a power steering system that is controlled on a needs only basis. The standard hydraulic power steering unit in the C-Class has an additional valve that switches off the servo pump when it is not required. While this pump operates continuously in all driving situations in conventional steering systems, the new valve interrupts the flow of hydraulic fluid when the car has followed a straight course for a given period of time and then the servo pump is switched off. Thanks to this technology, the NEDC fuel consumption is cut by another 1.1 mpg which equates to a reduction of 2.5 percent in the case of the C 200 CDI.

    Driver feedback

    A newly developed gearshift display in the cockpit informs the driver when he should change gears to save fuel. Experience gained during the Mercedes-Benz "ECO Training" courses has shown that drivers are able improve fuel economy by up to 15 percent with an economical and energy-conscious style of driving with the feedback provided.

    In addition to gearshift recommendations, the instrument cluster features a newly developed display showing the current instantaneous fuel consumption in the center of the speedometer as an easily legible bar graph. A brief glance at the display is sufficient to tell the driver the current fuel consumption in L/100 KM. The bar responds immediately when the driver changes to a higher gear or takes his foot off the accelerator to use engine braking with fuel cut.

    Key engine, performance and fuel consumption figures at a glance

    DisplacementOutputMax Torque0 – 60 (sec)Top SpeedNEDC fuel consumption*CO2 emissions
    2,148 cc136 HP@3,800 RPM199 Lb-Ft10.313646.1 mpgUS135g/km

    * NEDC Combined​

    All-in, a 42 mpgUS combined vehicle was turned into a 46.1 mpgUS combined vehicle with a few well thought out modifications without the driver experiencing anything different from the recently redesigned C-Class in terms of NVH, performance or driving experience. Who would have thought :)
    Last edited by a moderator: Feb 28, 2008
  2. toastblows

    toastblows Well-Known Member

    That is a nice ride...where can i buy one....oh only in europe :(

    im guessing its put together a lil better than my mexican made jetta :woot:
  3. sup'd

    sup'd Well-Known Member

    It's about time the luxury market comes out with a FE first vehicle.

    Don't you think for $60k a luxury manufacturer could produce a PHEV turbo diesel AWD (electric motor on each wheel) with both supercapacitors and Lithium Ion batteries for maximum regen and long/short term storage capacity ?
  4. toastblows

    toastblows Well-Known Member

    maybe for $100k ;)
  5. Right Lane Cruiser

    Right Lane Cruiser Penguin of Notagascar

    So this thing matches the Insight for CD? Impressive!
  6. antrey

    antrey Well-Known Member

    It's good to see alot of the aero mods hypermilers perform are right in line with what OEMs implement when they go for Aero efficiency. When I sealed between the hood and headlights and the bumper and headlights I thought I was grasping at very low hanging but also not very good fruit. Apparently it may have more of a beneficial effect than I assumed.
  7. Vooch

    Vooch Well-Known Member

    who is going to be the first to send this to Lutz, Nardelli, and Ford ?
  8. southerncannuck

    southerncannuck Well-Known Member

    Anybody have an ideal what kind of tires are on the car?

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