Mercedes Board Member demonstrates upgrades for new C-Class

  • 25-Mar-2014 07:39 EDT
Merc03-14 Ola Kaellenius.jpg

Mercedes-Benz Board member Ola Kaellenius says that for engineering reasons, the new C-Class moves up a segment.

The names Ola Källenius and Mercedes-Benz go together like a horse and carriage, or, in modern parlance, like a highly efficient, low emissions engine powering a weight-saving, exceptionally aerodynamic car.

A Member of Mercedes’ Board since last fall, Källenius was previously Chairman of the Management Board and CEO of Daimler’s Mercedes-AMG. His career path has also seen him as Head of Powertrain Procurement with Daimler; Head of Mercedes’ High Performance Powertrains (previously Ilmor) in the U.K.; positions with McLaren Automotive for the introduction of the exotic SLR; and Plant Manager at Mercedes’ Tuscaloosa, AL, facility. All this after first joining Daimler’s International Management Associate Program 21 years ago.

So when the multilingual Swede invited this Automotive Engineering editor to join him on a demonstration drive in the new Mercedes C-Class (previously described at this link) over the twisting, mountainous roads above Marseille in the South of France, it seemed unlikely that he would be at a loss for words.

He was not.

“For engineering reasons, we believe the new C-Class moves the game on—starting with its body design and construction,” he said as the C-Class, which incorporates AMG expertise, moves into action. “We call it 3-D body engineering, and our first target was to significantly reduce the weight. Coming from a steel platform with the 204 series C-Class to the 205 series, we have gone to 48% aluminum with regard to the area of the car. That takes 70 kg out of the BIW. But we tried to take weight out of every single component, too. So thanks to the efforts all our engineers have made, and in spite of the fact that the car has grown we took out another 30 kg around the car, for a sum total of 100 kg, which greatly benefits economy and driving dynamics.”

The car's wheelbase is stretched 80 mm (3.1 in) to 2840 mm (111.8 in) and overall length by 95 mm (3.7 in) to 4686 mm (184.5 in), with width expanding by 40 mm (1.6 in) to 1810 mm (71.3 in). Torsional rigidity is increased by some 13%.

The increased dimensions push the C-Class level with, or in some areas beyond, the size and interior space of the E-Class of the mid-1990s. It also projects the 205 series towards a higher segment than its previous grading, believes Källenius. In European terms, it now feels a big car.

While weight saving was one key area of focus, aerodynamics was another: “For some years, we have worked really hard to optimize the drag co-efficiency of our models, and a best Cd of 0.24 for the new car is class leading.”

Finer points of achieving this include use of intelligent, drag reducing lamella shuttering on the traditional Mercedes front grille (there is a choice for some markets of this or a large central three-pointed star) which has the added benefit of reducing engine warm-up time.

“Although aerodynamics are very important, it is necessary to protect our styling philosophy. It is a very symbiotic task shared between the aerodynamicists and the stylists. If you were just to have a hardcore aerodynamicist that didn’t regard the beauty of the car, it would not be a happy marriage. Our Head of Aerodynamics is Dr. Teddy Woll, who understands what is wanted.” The benefits in terms of reduced fuel consumption and emissions is considerable, emphasized Källinius.

“If we are able to reduce the Cd figure by ten thousandths, fuel consumption across the customer average falls by one tenth of a liter, and at very fast motorway speeds by up to 0.4 L/100 km," said Woll previously. "To achieve the same saving with lightweight construction measures, we would have to reduce the weight of our cars by at least 35 kg.”

He added that current digital vehicle models have over 50 million cells: “If necessary, they can produce results overnight. Ten years ago, the same simulation would have taken 6 months and would not have been half as precise.”

Getting much below 0.25 Cd without creating a car that looks distinctly odd, rather than just distinctive, is a tough call, although the best figure for Mercedes’ CLA sedan is an exceptionally good 0.22. However, Cd reduction taken to an extreme (0.20 or less) for a practical four-seat, medium- to high-volume vehicle, still means—at present—that no-one may buy the resultant product, said Kallenius. However, steady advances in underbody aerodynamic efficiency are helping without detracting from acceptable aesthetics.

The combination of aerodynamic efficiency (which also makes for very quiet high-speed cruising) and weight loss achieved with the new C-Class has made a major contribution to efficiency, said Källenius: “Looking at the diesel and gasoline powertrain range on average, we are taking about 20% out of the fuel consumption figures. The plain vanilla C220Cdi (2.1-L, 125 kW) is 103 g/km.”

The C-Class range will later see the addition of an 85-kW (114-hp) 1.6-L diesel that will achieve 99 g/km of CO2 emissions. The application is the result of a technology partnership with Renault, but Källenius insisted that it is not just a transplant: “Everything we put into our car is put through Mercedes’ engineering.”

Complementing the E-Class Hybrid, there is now a C300 BlueTec Hybrid with 2.1-L 150-kW (201-hp) diesel plus 20-kW electric motor, offering 94 g/km CO2, and combined provisional NEDC fuel consumption of 3.6 L/100 km. Next year this will be joined by a plug-in hybrid with 30 km (19 mi) pure electric driving range.

Although there is some carry-over from the 204 series C-Class (including powertrains, although they are updated with improved CO2 emissions), the 205 is essentially all new.

A significant aspect of the 205 series C-Class, which uses MRA (Mercedes Rear-drive Architecture), is the option of air suspension, a claimed first for its segment. The driver has a wide choice of chassis (including steering) tuning levels: Comfort, Eco, Sport, Sport-plus, and Individual, the latter allowing configuration of individual settings. Air suspension is another factor that takes the new C-Class into a higher segment, said Kallenius, as he demonstrated all of this with great enthusiasm on a wide mix of roads with varying surfaces and corner radii.

The C-Class’s segment hike also applies to the interior fit and finish, which makes the outgoing C-Class look very understated.

Interior details include what could be described as a perfume bottle fitted in the glovebox. In fact it is a climate system controlled air freshener giving the cabin a choice of three aromas. Mercedes calls it “active fragrancing.” Stated Källenius: “It’s a luxury detail not for everybody!”

As, perhaps, is the standard touch-pad mounted above the regular systems controller. Källenius regards its styling as “a piece of art.” Its functionality, though, may also not be for everybody, although Mercedes regards it just as complementary to the regular controller. What certainly will be for everybody is an excellent head-up display; clear, concise, and competent.

A large, opening panoramic glass sunroof is sure to be very popular; it is standard for some C-Class versions.

Driver assistance/support systems take functions from the new S-Class, combining data from various sensor technologies including a stereo camera to provide stop-go and semi-autonomous steering in traffic jams. The car can provide autonomous braking at speeds up to 200 km/h (124 mph) if a driver fails to take action as danger of a collision increases.

As we arrive at Cassis and the end of the drive, Källenius hands the car's keys to this Automotive Engineering editor, explaining the thinking behind the new C-Class’s exterior: “We have tried to make it ‘younger and sportier’ than before. What's the design definition of ‘sportier’? It is the stance of the car from any angle. But it is subtle; the car is bigger but does not look it.” The large star frontal treatment also appeals more to younger buyers than does the classic Mercedes grille, he believes.

And what of more technology to come? “Stop-go pilot is the first step towards autonomous drive and that is going to happen. Next step is the self-parking car. As for full-blown autonomous drive, our vision is that we will see it within 10 years, but the regulatory side has to be worked out. And law makers need to be hand-in-hand with us. But this is a task to be achieved—not an ultimate obstacle.”

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