Quietly Improving

General Motors Corp.'s goal of establishing Buick as a rival to Toyota Motor Corp.'s Lexus division often draws snickers. Buick's skeptics say the nameplate lacks Lexus' refinement, its sophisticated styling and its younger and more affluent buyers.

But there is at least one area where Buick legitimately is competing with Lexus: its vault-like interior sound management is absolutely stunning.

Road noise is totally muffled. Wind noise is nothing more than a gentle breeze. The engine proffers a distant and soothing hum.

Buick calls its sound-deadening efforts QuietTuning. Employing various technologies, QuietTuning debuted on the Rainier midsize SUV in 2003. Since then, the technology was rolled out in 2004 on the LaCrosse sedan and Terraza minivan. The Lucerne large car, on sale later this year, also will use QuietTuning.

Squeaks and rattles are becoming a distant memory, thanks to improved fit-and-finish. But lower noise levels also are achieved through the unique use of materials. QuietTuning was born during development of the LaCrosse, which was delayed by GM Vice Chairman Bob Lutz in 2002.

“Bob had an early review of the car, and he was not happy with the noise performance,” recalls Dan Nolley, performance manager-noise and vibration for the LaCrosse program. “He knew we were way off from providing a Lexus-type noise environment. So he did the best thing he could do. He put a letter out that said, ‘Whatever you need to do to make this car quiet, you are authorized to do.’”

Engine and tire noise were the most substantial issues with the LaCrosse's predecessors, the Regal and Century.

So GM made a move rare for the LaCrosse's segment, which also includes the Toyota Camry, Volkswagen Passat, Mazda6 and Honda Accord.

The auto maker is using Quiet Steel for the LaCrosse's dash. A technology often used in trucks — it debuted in 1999 on the Ford Explorer — Quiet Steel is a suite of engineered multi-layer composites with various elastic polymer cores between two layers of cold-rolled steel. Illinois-based Material Science Corp. is the supplier.

“It was a challenge mainly because we did it at the last minute,” Nolley says. “Quiet Steel is like a sandwich. It's two layers of steel separated by a visco-elastic layer, which you can really just think of as a goo that can be tuned for specific applications. With laminated steel you've got 100% coverage. There are no exposed corners or seams.”

Quiet Steel precludes the need to spray on damping materials or to employ thick foams.

In another uncommon move for the midsize car segment, LaCrosse uses PPG Industries' laminated side glass for the front-row windows. While offering the same thickness as typical glass at 0.2 ins. (5.1 mm), it essentially is a plastic material comprised of a glass and visco-elastic sandwich.

“Nobody else in the midsize car segment uses it,” Nolley claims. “We did specifically for wind noise, but the motor noise turned out unbelievably nice, too.”

LaCrosse's sound-management effort goes beyond isolating techniques. GM also tapped Collins & Aikman Corp. for acoustical tuning via its proprietary AcT Fiber absorptive carpet, which is used throughout the LaCrosse's cabin and trunk.

AcT Fiber is an advanced blend of inter-locked synthetic fibers customer-tuned for sound transmission loss and absorption applications. The acoustics are manipulated by controlling the length and blend of fibers.

“We went through iteration after iteration of AcT Fiber, because they can tune this stuff to different frequencies,” Nolley says. “We'll tell them, ‘We really need help at low frequencies.’ And they'll work really hard to tune their fiber to perform best at low frequency. We worked very closely with them and went through exhaustive development work.”

The noise-reduction efforts are paying off. GM's research indicates the LaCrosse's road noise is lower than the higher-priced Lexus ES 330 sedan, while engine noise is only slightly higher, Nolley says.

Plus, the quality of the sound entering the cabin is excellent. That is impressive considering one of the LaCrosse engines is the decades-old pushrod 3800 V-6.

“We've never done an application that has been this quiet before,” Nolley says. “That is the one that honestly impresses me the most. I've been working with 3800 engines for a long time. And that application is the quietest.”