The luxurious 2009 CL550 coupe (382 hp, 391 lb.-ft) will receive the latest version of the Mercedes-Benz 4MATIC all-wheel drive system as standard equipment. As modern all-wheel-drive systems become even more refined, they are increasingly popular, especially in the luxury car market. With negligible weight and fuel-efficiency tradeoffs, full-time all-wheel-drive systems provide year-round traction and stability benefits on both wet and dry roads.
The V8-powered 518hp CL63 AMG and the V12-powered 510 hp CL600 and 604 hp CL65 AMG models will continue with rear-wheel-drive powertrain. The 2009 CL line goes on sale in the summer of this year.
The Latest 4MATIC System
The latest 4MATIC system features a new-generation full-time all-wheel-drive system that’s integrated into the seven-speed automatic transmission. Having made its debut on the new-generation 2007 S-Class sedan, the system fits right into the standard CL body and utilizes the existing front suspension (gone are the special suspension parts and wider transmission tunnel that were necessary on earlier 4MATIC systems). The extra gears and shafts that drive the front wheels now weigh only 154 pounds more than the rear-wheel-drive model. Beginning from the right side of the transmission tail section, a driveshaft powers a front final drive and differential unit just to the right of the engine oil pan. The axle shaft for the left front wheel passes through a tube that’s encapsulated in the engine oil pan.
Improved Fuel Efficiency
Fuel efficiency has been improved, due to a number of innovative measures that minimize the energy needed to turn the extra all-wheel-drive shafts and gears. In particular, only two gears now power the front driveshaft (instead of the previous three), and the direction of rotation is cleverly corrected in the front final drive without additional gears. Recessing the universal joint for the front driveshaft into the transmission output gear also saved space, helping to fit the entire drive system into the standard body shell.
Full-Time 4WD System Features Four-Wheel Traction Control
The full-time four-wheel-drive system used in Mercedes-Benz 4MATIC cars and all sport utilities features a center differential that can vary front-to-rear torque distribution for great on-road handling, not to mention stellar traction. In addition, the system includes innovative four-wheel electronic traction control that keeps the vehicle going even if only one wheel has traction.
Even Better Traction with Multi-Plate Diff Clutch
Like the S-Class sedan, the CL550 4MATIC coupe comes with a multi-plate clutch tucked into the center differential that provides the extra traction benefits of a limited-slip diff while complementing its four-wheel traction control. Often called a “breakaway” clutch, the multi-plate unit helps provide power equally to the front and rear wheels when driving straight ahead, but still allows the front wheels to rotate faster in turns. While four-wheel traction control reacts after wheel slippage is sensed, the clutch helps prevent slippage.
4MATIC Cars Get Rear-Biased Torque Distribution
Under normal conditions, Mercedes sport utility vehicles distribute torque nearly equally between the front and rear wheels. However, 4MATIC-equipped Mercedes-Benz cars come with a planetary gear set within the center differential that begins with 45-55 percent front-to-rear torque distribution. To skilled drivers, this rear-bias all-wheel-drive system feels much like rear-wheel-drive cars, in which subtle throttle-steering effects can enhance handling, especially in spirited driving.
A Full Century of 4WD Experience
Mercedes-Benz has been building four-wheel-drive commercial vehicles since 1907 – a full 100 years of experience with all-wheel drive. The 4MATIC all-wheel-drive system made its world debut at the Frankfurt Motor Show in 1985, and Mercedes-Benz launched 4MATIC-equipped passenger cars in the U.S. market for the 1989 model year. The full-time 4MATIC system made its debut on the 1998 E-Class sedan and wagon as well as on the M-Class sport utility.
PRE-SAFE® Brake Can Automatically Apply Partial Emergency Braking
The launch of the current CL coupe marked the debut of another revolutionary Mercedes-Benz safety feature – PRE-SAFE® brake. The company that invented SRS, the crumple zone, ABS anti-lock brakes, traction control and ESP stability control also launched PRE-SAFE on the S-Class sedan in 2002. On the latest CL, PRE-SAFE, in combination with the Distronic Plus system, now also comes with the ability to automatically apply partial braking in certain types of emergencies.
Standard on all CL coupe models, the revolutionary PRE-SAFE® system automatically tightens the front seat belts during the valuable seconds just before a possible impact, and the front passenger seat moves to a position that can provide better protection. And, if the system senses an impending rollover, the sunroof closes as well.
Side windows also close to provide better support for the window curtain air bags, and special seat cushions can inflate to provide greater lateral support for occupants and to help the side air bags provide even better collision protection.
Distronic Plus Helps in Stop-and-Go Traffic
In the latest CL coupe line, the well-known Distronic cruise control feature that maintains a pre-set following distance behind the vehicle ahead is replaced by an optional “Distronic Plus” system. Integrated with the latest PRE-SAFE, the latest radar-based system operates at nearly all speeds up to 125 mph and can be especially helpful in stop-and-go traffic. Newly developed short-range radar sweeps the first 33 yards in a fan-shaped 80-degree pattern, working in tandem with a narrower nine-degree beam of longer-range radar.
The two radar frequencies complement each other to cover a full range of more than 160 yards – more than 1½ football fields. During approval of the new 24-gigahertz radar frequency, government agencies cited its potential to improve traffic safety, reduce injuries and ultimately save lives.
Blind Spot Alert Also Helps Make Driving Less Stressful
As a new option in conjunction with Distronic Plus, a blind spot alert system monitors those hard-to-see areas in adjacent lanes, to help make changing lanes safer and, in general, make driving less stressful. What’s more, when other vehicles enter the blind spots on either side of the CL coupe, a red warning light imbedded in the outside mirror alerts the driver. And, if the driver doesn’t notice the warning and operates the turn signal as a prelude to changing lanes, the system then blinks the mirror warning light and sounds an alarm.
The blind spot alert system uses six short-range radar sensors (four in the rear bumper and two in the front) to sense overtaking vehicles as well as vehicles that have already been passed. Monitoring the zone to the side and rear on the left and right, the blind spot alert system works at any speed above 18 mph.
Radar-Based Park Assist
Distronic Plus also incorporates radar-based Park Assist that provides a warning tone and a visual readout of the distance to adjacent parked vehicles. This option utilizes the same radar sensors mounted in the bumpers, and its clean look replaces the visible “portholes” of the previous ultrasonic-based system.
An optional rear view camera also helps makes reverse parking easier and safer. Whenever reverse is engaged, a camera hidden just above the license plate displays the area behind the car on the COMAND screen, and lines that change with steering input are shown on the display to assist the driver in parking maneuvers.
Brake Assist Now Teams Up With Distronic Plus
In the early 1990s, Mercedes-Benz engineers conducting simulator tests discovered that many drivers don’t push the brake pedal hard enough in emergency braking, a discovery that led to the development of Brake Assist, standard equipment on all Mercedes-Benz vehicles since late 1990s. Brake Assist has proven itself a million times, and tests show vehicles equipped with Brake Assist are involved in 26 percent fewer accidents.
On the latest CL coupe, an enhanced version of the Mercedes-Benz Brake Assist system not only supplies braking assist in emergencies as soon as the driver applies the brake pedal, but also measures the distance to the vehicle ahead (thanks to Distronic Plus) and adjusts brake pressure if the driver doesn’t brake hard enough. While Brake Assist is only triggered by the driver’s reaction on the brake pedal, Brake Assist Plus also considers the closing speed of the vehicle ahead based on radar signals from the Distronic Plus system.
In extensive tests conducted by Mercedes researchers using 300 drivers, the integrated system reduced rear collisions in heavy city traffic by 75 percent. During testing, data recorders and video cameras documented more than 250,000 real-world miles covered by 200 drivers in the U.S. and Europe, while 100 drivers participated in months of intense testing on the DaimlerChrysler driving simulator in Berlin.
Infra-Red Night View Assist
Another innovative technology on the CL coupe is optional Night View Assist, which can extend the driver’s ability to see ahead to nearly 500 feet. In contrast to passive systems that rely on thermal imaging, this active system bathes the road ahead with invisible infra-red light from two projector beams mounted in the headlights. An infra-red camera discreetly mounted in the windshield receives the reflected images and displays them in a high-resolution display in the instrument cluster. The result is akin to a highly detailed black & white video image.
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