Although photos of the all-new 2014 GMC Sierra 1500 in Crew Cab and Double Cab configuration have been readily available for months, the first images of a Regular Cab version of the division's full-size pickup only materialized this week. These first official pics show the baseline 2014 Sierra 1500 undergoing an evaluation session in GM's 750-foot long windtunnel at the automaker's state-of-the-art Aerodynamics Lab.
Like its Chevy Silverado 1500 cousin, the new Sierra has been subjected to more intensive drag-reducing effort during its early development stages than any other pickup in the automaker's history in an attempt to bolster its fuel economy and create a quieter and more refined passenger compartment. According to GM aerodynamic performance engineer Diane Bloch, meeting that challenge led to some interesting discoveries about what kind of elements figure into the overall optimization process.
"The biggest misconception is that it's all about single components," noted Bloch. "But a certain side mirror design doesn't create a certain amount of drag, its interaction with the rest of the vehicle does." Beyond obvious features like a front air dam that effectively channels air away from the underbody, the Sierra clean-up entailed far more subtle tweaks that ranged from optimizing the contours of the top of the tailgate and the center high-mount stoplight, to designing a special seal to help bridge the gap between the cab and bed -- which computational analysis showed to be a particularly critical area with respect to the creation of disruptive flow patterns.
According to Bloch, the new Sierra, as well as any other pickup, actually presents a more aerodynamic profile with its tailgate in the upright position, and replacing it with an aftermarket cargo net is even worse than just removing the tailgate completely. She also advises that a bed cover will help smooth flow patterns, and that a soft tonneau is actually more effective that a rigid one. Running boards also can contribute to the wind-cheating process, with fully integrated, flush-mounted units being superior to tube-style alternatives. Conversely, things like bug deflectors, wider tires and aftermarket bumpers have the opposite effect, and tend to increase cabin noise levels as they diminish your mpg.
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