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Mercedes to Introduce BlueEFFICIENCY C-Class Models; Fuel Consumption Reduction of Up to 12%

Blueefficiency
The C 350 CGI BlueEFFICIENCY.

Mercedes-Benz will add three fuel-efficient variants to its C-Class range: the C 180 KOMPRESSOR, C 200 CDI and C 350 CGI BlueEFFICIENCY models. Fuel consumption of the high-volume C 180 KOMPRESSOR and C 200 CDI models will be reduced by up to 12%.

The BlueEFFICIENCY version of the 100 kW/136 hp C 200 CDI consumes 5.1 liters of diesel per 100 kilometers (46.1 mpg US), while the C 180 KOMPRESSOR BlueEFFICIENCY with 115 kW/156 hp covers 100 kilometers with 6.5 liters of premium gasoline (36.2 mpg US). This corresponds to 135 and 156 grams of carbon dioxide, respectively, per kilometer. The C 350 CGI BlueEFFICIENCY features spray-guided gasoline direct injection and burns around 10% less fuel than the model with the current V-6 engine.

Engines. For the C 180 KOMPRESSOR, Mercedes-Benz has reduced the overall displacement of the four-cylinder engine from 1,796 to 1,597 cubic centimeters, while retaining the same output (115 kW/156 hp) and torque (230 Nm/170 lb-ft). This downsizing of the engine’s displacement, combined with measures for optimizing the combustion chamber, mixture formation and engine friction, adds up to a total potential fuel saving of 0.35 liters per 100 kilometers. The 6.5 L/100km fuel consumption of the C 180 KOMPRESSOR BlueEFFICIENCY is 0.9 liters (12%) less than for the standard production model.

The displacement, output and torque of the CDI engine remain unchanged. The package of efficiency measures (below) has enabled the NEDC fuel consumption of the BlueEFFICIENCY version of the C 200 CDI to be cut by 0.6 liters (10.5%) to 5.1 L/100km.

The new C 350 CGI BlueEFFICIENCY is equipped with a 3.5-liter spray-guided gasoline direct injection engine with a compression ratio of 12.2. (Mercedes-Benz became the first car maker to put spray-guided direct gasoline injection into series production in 2006.) Despite generating a higher power output and even greater torque, the new model consumes around 10% less fuel than the C 350 saloon with the current V-6 engine.

The six-cylinder CGI engine delivers 215 kW/292 hp of power and 365 Nm/269 lb-ft of peak torque at 3,000 rpm—15 kW/20 hp and 15 Nm/11 lb-ft more respectively than the current V-6 unit with port injection. Fuel consumption of the C 350 CGI BlueEFFICIENCY has been cut to approximately 8.4 L/100km (28 mpg US), about 1 liter below the figure for the current C 350.

The C 350 CGI BlueEFFICIENCY takes 6.2 seconds to accelerate from 0 to 100 kph and is capable of an electronically limited top speed of 250 kph/155 mph (provisional figures).

The six-cylinder engine demonstrates its particular strengths during stratified-charge operation when the powerplant operates with a high excess of air and is thus very fuel-efficient. In the Mercedes direct injection engine, this favorable lean-burn operation with a stratified charge in the combustion chamber is also possible for the first time at higher engine speeds and load ranges because the engine’s combustion chambers are injected with several successive jets of fuel in fractions of a second during each power stroke, thereby substantially improving mixture formation, combustion and consumption.

Whereas stratified-charge operation was previously only feasible over a limited partial load range, the CGI six-cylinder engine can now be operated in stratified charging mode over a wider range.

High-speed, ultra-precise piezoelectric injectors are among the key components of the second-generation direct gasoline injection system. The piezoelectric valves open their injectors outwards to create an annular gap just a few microns wide, allowing the fuel jet to form with a uniform, hollow cone-shaped pattern. With millisecond switching times, the piezoelectric injectors also permit the multiple injection that promotes lean-burn operation and helps optimize conditions to deliver the engine’s consumption figures.

A high-pressure pump with downstream distributor and pressure valve supplies the fuel and regulates the amount delivered in accordance with requirements. With a pressure of up to 200 bar, the system develops around 50 times the fuel pressure of a conventional port-injection system.

Measurements show that untreated emissions (hydrocarbons) are reduced by more than half in the warm-up phase. Active control of injection and combustion also produces higher temperatures in the exhaust manifold, thereby warming up the catalytic converters faster.

Four-valve technology, variable camshaft adjustment for the intake and exhaust sides, two-stage intake manifold, balancer shaft and an intelligent heat management system with map-controlled thermostat are some of the other technical highlights that the direct injection engine has adopted from the port-injected C 350 engine. The crankcase and cylinder head are made out of aluminium; the cylinders are fitted with low-friction, dimensionally stable liners made out of a lightweight aluminium-silicon alloy.

For the new BlueEFFICIENCY models, Mercedes engineers also reduced weight, aerodynamic drag and rolling resistance and organized the onboard energy management more efficiently. Together, these measures add up to a fuel saving on the NEDC driving cycle of 0.9 liters per 100 kilometers for the C 180 KOMPRESSOR, and 0.6 liters for the C 200 CDI.

Lightweighting. Mercedes managed to shave off between 19 and 32 kilograms of weight depending on the model. This is in part due to a newly developed windshield made of laminated glass, which weighs around 1.2 kilograms less than before. This is made possible by a technology transfer from the Maybach luxury sedan: between the panes of glass is 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 noise comfort in any way.

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

Forged lightweight wheels also have a positive effect on the weight. These weigh around 1.8 kilograms less than conventional light-alloy wheels, saving a total of more than seven kilograms per vehicle. These new lightweight wheels (6 J x 16 ET 39), which have aerodynamic benefits too, are standard equipment for the new BlueEFFICIENCY variants of the C 180 KOMPRESSOR and C 200 CDI.

Aerodynamics. At 120 kph/75 mph, the aerodynamic drag of the vehicle body already accounts for around 50% of all the dynamic resistance a passenger car must overcome, according to Mercedes. With a Cd of 0.27, the C-Class is among the most aerodynamically efficient notchback saloons in its market segment. The Cd figure for the new BlueEFFICIENCY models has been reduced by 7% to 0.25. Aerodynamic enhancements include:

  • Smooth underbody cladding ensures that the air can flow beneath the vehicle body without turbulences. The full engine compartment and underbody panelling of the diesel models is also standard equipment in the BlueEFFICIENCY version of the C 180 KOMPRESSOR.

  • Partially blanking off the radiator grille reduces the airflow into the engine compartment, thereby lowering wind resistance. Adequate cooling of the four-cylinder engines is of course uncompromised by this measure.

  • Sealing the joins between the hood and headlamps, as well as between the bumper and headlamps, improves the airflow around the front end.

  • The housings of the exterior mirrors were developed in the wind tunnel, and are particularly streamlined in form.

  • Lowering the suspension by 15 millimeters reduces aerodynamic drag, and has a particularly noticeable effect at higher speeds.

  • The design of the new lightweight wheels also meets aerodynamic requirements, and improves the airflow around the vehicle flanks.

Rolling resistance. In addition to lightweight construction measures, Mercedes-Benz also collaborate with Michelin to develop lightweight tires with a particularly low rolling resistance. These are now receiving their series production premiere in the C-Class, and help to reduce fuel consumption.

Rolling resistance is primarily caused by tire deformation as the tire contacts the road surface. This has a braking effect on the car, since additional energy is required to overcome this deformation resistance. Up to around 100 kph, rolling resistance has a greater effect on fuel consumption than aerodynamic drag, according to Mercedes.

The belt of this newly developed tire for the C-Class contains a multi-layered mesh of high-strength steel for less deformation. It is also lighter in weight than conventional designs, enabling a further 1.7 kilograms or so to be saved per set of tires. The secret, however, mainly 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%, while retaining the same good handling and braking characteristics.

Energy management. Intelligent control of ancillary units and the reduction of friction losses also contribute to the increased fuel economy. In the BlueEFFICIENCY models of the C-Class, the power steering system is controlled on a needs-driven basis. The standard power steering in the C-Class has an additional valve which 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 while, switching off the servo pump. This has the advantage that the engine no longer needs to provide energy to drive the servo pump, meaning that it operates more economically. Thanks to this technology, the NEDC fuel consumption is cut by 0.14 liters per 100 kilometers&mash;which equates to a reduction of 2.5% in the case of the C 200 CDI.

Drive and transmission. As a further contribution to reduced weight and friction, the BlueEFFICIENCY C 180 KOMPRESSOR and C 200 CDI saloons are equipped with a newly developed final drive featuring further-improved antifriction bearings, forged differential gears and a lightweight construction. These measures reduce the friction forces within the transmission, hence the engine expends less energy in overcoming them. The longer final-drive ratios of the BlueEFFICIENCY versions also help to reduce fuel consumption. These are as follows:

  • C 180 KOMPRESSOR: 2.87 : 1 (rather than 3.07 : 1)

  • C 200 CDI: 2.47 : 1 (rather than 2.65 : 1)

The C 180 KOMPRESSOR and C 200 CDI models are both equipped with the six-speed manual transmission with overdrive characteristics as standard. With a ratio of 0.838 : 1 and 0.828 : 1, respectively, sixth gear considerably lowers the engine speed, contributing to more fuel-efficient driving.

A newly developed gearshift display in the cockpit informs the driver when he or she should change gear to save fuel. Experience gained during the Mercedes-Benz ECO Training courses has shown that drivers are able to make average fuel savings of up to 15% with an economical and energy-conscious style of driving. In addition to gearshift recommendations, the instrument cluster features a newly developed display showing the present fuel consumption. This will appear in the centre of the speedometer as an easily legible bar chart. A brief glance at the display is sufficient to tell the driver the current fuel consumption in liters per 100 kilometers. The bar chart responds immediately when the driver changes to a higher gear or takes his foot off the accelerator to use the deceleration fuel cut-off function.

Comments

John Taylor

If you can afford drive a Mercedes, then the cost of fuel is not a big issue, so it is really nice to see that Mercedes "gets it" that a lot of people WANT to be green and responsible in their choices.

Kudos where due!

Anne

If rolling resistance was reduced by 17% and aerodynamic drag by 7%, then this alone can already account for the 12% reduction in fuel consumption. To be more accurate, the improvements in energy management already account for 2.5%, leaving 9.5% to be accounted for.

So I must draw the conclusion that the engine improvements had a negligable effect.

daniel billinton

i would agree that the total redctuiosn fo 10 to 12% seem to be less than the sum of the parts, so to speak.

These 'variants' seem very similar to BMW's efficientdynamics programme which achieve gains of 15-20% - except that these apply to 95% of the BMW range

mercedes wil probably be hit the hardest by forthcoming EU CO2 targets and it has launched these measures much later than BMw so it behind with the game.

Really merceded needs to make these measures standard on all vehicles across their entire range for it to have the slightest chance of meeting the EU's 139g CO2/km target that has been set for them under a weight based system.

Daniel

Rafael Seidl

Small fry does add up, but unfortunately not perfectly. Combinations of measures usually generate a smaller aggregate effect than their individual gains would suggest. Still, 10-12% amounts to a substantial amount of relatively low-hanging fruit and, it doesn't even include stop-start and intelligent alternator functionality yet.

Daniel's argument that Mercedes should take its cue from BMW and make these features standard on all of its models is valid. With no way to opt out, buyers can be confident that others will also be doing their bit for the common good - in this case, energy security and the climate. Savings at the pump alone usually don't provide sufficient motivation in this vehicle segment, what counts is how the choice is perceived by their social peers.

Unfortunately, many of them still prefer to spend their money on performance and luxury options rather than on efficiency. Greened-up versions of regular models still tend to sell poorly. Making the features standard would enhance brand image in the long run but could cost market share and/or depress profit margins in the short term. With domestic sales down for virtually all of the German brands and Mercedes' exposure to the very weak dollar in the important US market, that's a business risk the brand decided not to take at this time.

The upcoming EU fleet average CO2 emissions regs should alleviate this issue because competitors in the premium segment will also have to prioritize efficiency. Unfortunately, changing customers' perceptions of what constitutes added value is always a slow process.

Lad

I have always enjoyed watching the way EU auto makers allow their engineers to innovate and have always thought them to be engineering companies first rather than bean counters. I think the U.S. auto companies count beans first...look how long the U.S. push rod engines have lasted...look at NASCAR's Car of The Future; wow! boy! now that's pure U.S. innovation at it's best. But then, I guess if all you are doing is racing in one direct you don't need all that fancy innovation stuff.

realarms

Nice to see, that one of the cheapest, and most effective way to reduce consumption has been implemented at last also by mercedes (last three sentences). It`s well known, that driver behaviour can impact consumption by as much as 25% - giving a proper feedback (obviously exactly the same way Toyota choose in 1997 for the Prius), with a short-term history bar-graph and a immediate measurement in an easy to comprehend way is key to educate drivers.

However, for the gear-shift indicator, with need to give kudos to the EU commission, making this a requirement by law by mid-2009 for all new cars sold here... (interesting, that every single car manufacturer markets this as his own great achivement - the same old game as catalytic converters, safety belts, air bags all over again; obviously sometimes it needs the regulators influence...)

LEO WELLS

REDUCE FUEL USEAGE 50%

Put a contsiner of water under your hood. Stick in 2 electrodes, one to ignition, one to ground. That makes hydrogen and oxygen. Run a tube to the vacumn line, that will take the hudrogen and oxygen to the motor. This could double your mpg.

How much does water cost????

Dave

Hey LEO, enough with you spamming the comments, eh?

Good work Mercedes, the Cd is impressive (0.25) and beats the Prius (0.26)!

I wonder if Toyota put all the aero tricks into the Prius that Mercedes put into the BlueEFFICIENCY models what they could achieve? It seems that there is room on the Prius to reduce the drag a few more hundredths with better cooling and underbody air management.

Bill W

VW started using (and others) shift-up indicators in the dash during the late 70's/early 80's, the past time when efficiency was cool.

Allot of the current effort is so 80's, when every manufacturer had a efficiency special that was stripped of options, had tall gearing, skinny tires and a little spoiler on the trunk to improve aerodynamics. It is a bit different know, but the similarities are striking.

Patrick

Bill,

Lets hope the follow on to the 80s (the 90s with the birth of SUVs and reignition of the horsepower wars) don't also get copied...

LEO WELLS

DAVE

YOU MAY BELIEVE THAT THE AUTO'S ARE MAKING BREAK THROUGHS BUT THE REAL BREAKTHROUGH IS THE ABILITY TO RUN YOUR CAR ON WATER WHEN THERE IS NO MORE OIL.

Stan Peterson

This illustrates that there is more efficiency to be wrung from the ICE,and ev ery improvement adds to teh efficiency. But in the long run, these advances will not prove decisive. Substitution of a new fuel is what is required ot supplement liquiid hydrocarbons from whatever source.

Electricitry has the advantage of being produceable from many source fuels and even from so-called renewables (which really are not).

But it is clear that as long as the ability to use the biological computer positioned between the ears, that substitution will come as it has for a myriad of other products in short supply. Everything from scarcity of flints for our cro-magno forefathers; to the "cedars of Lebanon" and "good English Oak" for our historic seafaring predecessors.

pSyCh0

HEY LEO, CAN YOU READ THIS? GREAT. YOU'RE A CRIMINAL LEO. IF YOU KEEP IRRITATING US WITH YOUR SPAM, ONE OF OUR HACKERS MIGHT TAKE DOWN YOUR FRAUD SITE. WE MIGHT TURN YOU IN TO THE FEDS, TOO. GET LOST.

LEO WELLS

pSycHo THANK YOU FOR YOUR INSITE

AS SMART AS YOU ARE, MAYBE YOU CAN HELP ME LET THE AUTO MANUFACTURERS AND THEIR ENGINEERS KNOW THAT WITH THE ALTERNATORS AND ELECTRICAL SYSTEMS WE HAVE IN VEHICLES TODAY, WE CAN MAKE HENRY FORD'S INVENTION "RUN A CAR ON HYDROGEN ELECTROLIZED FROM WATER" WORK IN TODAY'S VEHICLES...BEFORE WE RUN OUT OF OIL, OR WORSE, CAN'T AFFORD TO BUY FORIGN OIL IMPORTED FROM OVER SEAS

LEO WELLS

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