Grand Cherokee’s Quiet Cabin Echoes Marchionne’s Resolve

SAUSALITO, CA – Chrysler Group LLC’s product-development team considered making quiet cabins an option in the all-new ’11 Jeep Grand Cherokee, particularly for international-market versions powered by diesel engines.

But under the regime of CEO Sergio Marchionne, Chrysler does not compromise on attributes the customer values most. So the decision became clear, says Grand Cherokee Chief Engineer Phil Jansen.

“We’ll make everything a premium package,” Jansen tells Ward’s here during a media preview of the iconic SUV’s latest iteration.

This means every trim level – Laredo, Limited and Overland – benefits top-to-bottom from myriad sound-deadening features such as laminated glass skylights and belly pans.

Chrysler uses an “articulation index,” which measures the ability to hear speech, as a yardstick for interior noise, vibration and harshness. And the auto maker says the redesigned Grand Cherokee boasts a 12% improvement over its previous generation.

The gains begin with the vehicle’s architecture, a tangible legacy of Chrysler’s days in the domain of now-defunct DaimlerChrysler AG. Conceived with Mercedes-Benz, it is expected to shoulder the tri-star brand’s next-generation M-Class cross/utility vehicle, which is scheduled for redesign in ’12.

With some 5,400 body welds, more than twice as many as the outgoing model, the new Grand Cherokee’s torsional stiffness is 146% greater.

In addition, the SUV boasts more than 146 ins. (370 cm) of arc welding and 328 ft. (100 m) of structural adhesive, increases of 42% and 38%, respectively, as Chrysler claims its all-new SUV is stiffer than the BMW X5 and Toyota Highlander CUVs.

Grand Cherokee sunroof features laminated glass.

But the benefits of Chrysler’s experience with Mercedes do not end there. “The full double-dash construction, which was really new to us, was something we picked up,” Jansen says.

The ’11 Grand Cherokee features sound-deadening on both sides of the dash panel, in addition to an acoustic wall placed 6 ins. (15 cm) from the engine.

Chrysler’s new Pentastar V-6, which is expected to be the volume engine, affords NVH advancement on its own. Idle behavior portends refinement because of dual-independent cam phasing.

“Underneath the car, we put silencers beneath the tunnel, on top of the tunnel and thicker carpet inside,” Jansen notes, adding heat shields and wheel-well liners also received upgrades.

The wheel-well liners, supplied by Germany-based Carcoustics International GmbH, are crafted from a durable fiber seen only on luxury-brand vehicles such as Audis.

When stones hit the liners, as happens frequently with vehicles featuring rugged tire designs, the sound is muffled.

Jansen says the ’11 Grand Cherokee represents Jeep’s first application of acoustic wheel-well liners.

CommandView, a dual-pane sunroof new to Chrysler in ’11, features sound-deadening laminated glass. The system consists of two glass panels, one in front that opens and a second that remains fixed to allow light into the rear passenger area.

Chrysler also attributes the Grand Cherokee’s quieter cabin to improved aerodynamics, which stem from 250 hours of wind-tunnel testing. To help trim the SUV’s drag coefficient to 0.37 from the ’10 model’s 0.40, a conical shape was applied to the SUV’s A-pillars, a removable front air dam was added and belly pans were employed, one in front and one on each side.

Consumers have high expectations when it comes to refinement, a preference reflected in high-profile efforts to reduce cabin noise, such as GM’s Buick-brand Quiet Tuning initiative.

“Wind noise is the single-most reported problem,” says David Sargent, vice president-global vehicle research, J.D. Power and Associates. “It’s a nagging thing.”

Though it is not a “deal-killer,” Sargent adds.

But Marchionne has suggested everything is on the table when it comes to satisfying customers. In a statement released as he presided over a Grand Cherokee Job One ceremony last month, he said: “Jeep Grand Cherokee is a signature vehicle for Chrysler. It represents the best of this company, the direction we’re moving toward producing high-quality, technologically advanced vehicles.”

Asked if the acoustic wheel-well liners will migrate to other Chrysler products, Jansen says:

“You can see where we’re heading.”

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