A key element of the 2014 Sierra is a wonderfully quiet interior. GMC made several changes to the cabin to accomplish this. The previous Sierra used doors that wrapped over the edges of the roof. Now, the doors are inlaid, a feature that improves aerodynamics and reduces turbulence. That means that there is significantly less wind noise. Another advantage to the new doors is that because the engineers changed the layout of the doors, that allowed them to make them triple-sealed.
Triple-sealing doors is a feature that has typically only been seen on high-end, luxury vehicles, GM anticipates the low levels of wind noise will unsurpassed by any truck in its class. These aren’t the only new aspects of the Sierra’s interior that make it quieter. GMC also used generous amounts of sound-deadening material throughout the cabin. And the results have been quite positive: GMC owners, including Gary Mills, gave the quiet interior a rave review. He noticed the interior was dramatically quieter than in previous models. A final touch that also makes the interior quiet: the engineers made the windshield angle more aerodynamic to further reduce wind noise.