NAIAS Highlights: Production
Mercedes-Benz expands its C-Class, again
The C32 AMG and the C320 wagon, both 2002 models, are being added to Mercedes' already impressive C-Class lineup. The C32 AMG is the first model from Mercedes-AMG, the high-performance division of Mercedes-Benz, based on the C-Class sedan. Powered by a newly developed, 260-kW (349-hp), 3.2-L supercharged and intercooled V6 Kompressor engine, the C32 AMG generates 450 N•m (332 lb•ft) of peak torque. The V6 engine uses a positive-displacement, Lysholm-type supercharger with scrolling aluminum rotors that provides usable boost from almost idle speed. The rotors are teflon-tipped for more positive sealing, quiet operation, and long life. The Kompressor V6 also uses a specially developed cross-flow air-to-water intercooler that reduces intake air temperatures, making for a denser charge. Other unique engine developments include a model-specific throttle body, revised cam timing, high-rate valve springs, and lightweight valves. Acceleration from 0-97 km/h (0-60 mph) is estimated at 5 s.
Under heavy braking, the new SpeedShift five-speed transmission automatically downshifts, selecting the optimal gear for the situation. Also, when the driver tips and holds the gear lever to the left, the transmission determines the best possible gear for maximum acceleration in any situation. The transmission also holds a selected gear under high cornering loads, which prevents an upshift in mid-corner. A new, lightweight torque converter can lock up in all forward gears. According to Mercedes-AMG, SpeedShift provides up to 35% faster gear changes than a conventional automatic transmission.
Mercedes-AMG's racing experience influenced the C32 AMG's two-piece front brake discs, which measure 345.4 mm (13.6 in) in diameter. The brakes are vented, cross drilled, and mounted on a circle of steel pins to minimize heat transfer from the discs to the hubs, spindles, bearings, and wheels themselves. Rear discs, 299.7 mm (11.8 in) in diameter, are also vented. A four-channel, antilock braking system is standard (as on all Mercedes-Benz passenger vehicles).
The C32 AMG's chassis is thoroughly transformed from the basic C-Class design to provide the handling feedback and grip dictated by the supercharged V6 driveline. Spring rates are increased, shock damping is heightened, and stabilizer bars are tailored to the C32 AMG. In addition, newly designed, double-spoke, light alloy wheels - 7.5- x 17-in front and 8.5- x 17-in rear - wear 225/45ZR17 and 245/40ZR17 tires, respectively. These wheels also use air to enable brake component and hub cooling under extreme use.
The C320 wagon was developed in accord with the C-Class sedan, and they share many of the same technologies. The versatile wagon, powered by a 160-kW (215-hp), 3.2-L V6 with low exhaust emissions, allows one or both of the split rear seats to be folded forward to create a flat loading area. Cargo capacity ranges from 470 L (16.6 ft3) with the rear seats up to 1384 L (48.9 ft3) with them down. The C320 has "fastback" styling, and at the top of the wagon's tailgate is a discreet, integrated spoiler that enhances its aerodynamics and high-speed handling.
The C-Class wagon, like the sedan model, has a standard, electronic five-speed automatic transmission with Touch Shift, which allows the driver to manually select all five forward speeds by pushing the gear lever slightly left to downshift or right to upshift while in drive. Computer control prevents downshifts that would cause the engine to overrev. The transmission not only adapts automatically to changes in road grade (i.e., delaying upshifts on ascents for climbing power and hastening downshifts on descents for engine braking), but also to an individual's driving style while in fully automatic mode. For example, the transmission computer adjusts shifting logic for leisurely driving with smooth upshifts for the best fuel efficiency.
The wagon's new front suspension uses two separate lower links that are combined with a strut, coil springs, twin-tube gas shocks, and a stabilizer bar. By using two low-mass lower links rather that one large control arm, better impact absorption is provided in the case of a frontal impact. In addition, sensitivity to potential wheel imbalances or brake fluctuations is minimized. The C320 wagon's rack-and-pinion steering also aids absorption of crash energy with its lateral rack mounted ahead of the front wheels' centerline on a deformable aluminum subframe.
The steering wheel provides the driver with large, conveniently placed rocker buttons for an easy way to control many of the car's systems. Four rockers control a multifunction LCD display within the speedometer and can adjust more than 50 different functions, including the audio system, trip odometers and the trip computer with fuel tank range, clock, interior and exterior light dimming, and system language. In addition, three analog gauges monitor engine speed, road speed, and fuel level, while the multifunction display can call up other detailed information such as water temperature and oil level.
- Ryan Gehm
