C-class gets an overhaul

Frankfurt-For the newly revamped Mercedes-Benz C-Class, it's something borrowed, something new.

With a price tag under $36,000, the company's latest take on entry-level luxury borrows more than 20 engine, chassis, safety, and comfort features from the company's top-of-the-line S-Class. But as Jurgen Hubbert, the DaimlerChrysler board member responsible for passenger cars, points out, the new C-Class "is not a pocket-sized S-Class." Instead, it sports some new technology of its own-including a six-speed manual transmission on some models.

Launched here in May, the C-Class makes its North American debut this month with two models, the C240 and the C320. Here's a look at the engineering highlights:

More gears. If you think that Mercedes only have automatic transmissions in this country, think again. The new C240, which sports a 2.6-liter V6 engine, optionally comes with a six-speed manual transmission-the only one available in North America for nearly a decade. The new manual transmission shortens the first gear for better acceleration while keeping an overdrive gear for the highway. According to Jurgen Bollmann, head of design for the C-Class, the multiple-cone synchromesh design lowers shift forces by 25% and eases shifts between second and third and between fourth and fifth.

The larger C320, which has a 3.2-liter V6 engine, comes only with an automatic transmission. Its one-touch gearshift has been adapted from the S-Class.

Sleeker body. The new C-Class models achieve the company's best aerodynamic performance to date with a Cd of just 0.26. "It's our lowest at the moment," notes Hubbert. Compared to previous models, the new C-Class sedans offer a 13% drag reduction and a 57% drop in front and rear body lift, Bollmann reports. The new C-Class also beats the high-end S-Class and E-Class, both of which have a slightly higher Cd of 0.27.

Several newly designed body components play a role in cutting drag-inducing turbulence and reducing lift. These include a front air dam, a rear skirt, spoiler lip on the trunk, wheel spoilers, and encapsulation of the underbody and engine compartment.

Power and low emissions. Both C-Class models take advantage of existing Mercedes engine technology with all-aluminum engines that employ dual-resonance intake manifolds and three valves per cylinder-two intake and one large (41 mm head diam.) exhaust valve. The dual-resonance system contributes to a 20% higher output and 43% torque improvement over previous engines, Hubbert reports.

And the twin-spark, three-valve arrangement takes aim at emissions. As engine development chief Markus Schutz explains, the single exhaust port has less surface area than two valves and thus operates at a higher temperature so that some combustion remnants burn up before they reach the catalytic converter. What's more, the higher exhaust temperatures (roughly 125F) mean earlier "light-off" of the catalytic converter. As a result, emissions fell by 40% under those of a comparable four-valve engine, Schutz adds.

Safety first. The new C-Class comes chock full of safety features. Many-such as side-curtain airbags, energy absorbing body, and electronically controlled tensioners on front and rear seats-have been adapted from the company's top-of-the-line vehicles. One new feature on the C-Class is a set of crash boxes located on the front and rear crossmembers. Made from high-tensile-strength steel, these replaceable boxes absorb crash energy in collisions up to 9 mph.