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2019 GMC Sierra AT4 gives Raptor and Ram a new off-road rival

The 2019 GMC Sierra AT4 blends off-road hardware into a modern, thoroughly updated pickup truck that doesn't skimp on power, luxury, or safety equipment. From its higher suspension setup to its available carbon-fiber cargo bed and the new MultiPro tailgate, the 2019 Sierra AT4 is a direct shot across the bow — or cargo beds, if you prefer — of staunch rivals like the Ford F-150, Dodge Ram and Toyota Tundra. Revealed tonight in New York City, ahead of this week's New York International Auto Show, the truck may seem to be in a strange setting. Then again, with the amount of tire-swallowing potholes currently scattered around the Big Apple, a rugged truck like the Sierra AT4 could be the perfect vehicle for either off-road excursions or an especially bumpy commute. Riding two inches higher than the standard 2019 Sierra, the AT4 comes with standard features like all-wheel-drive with a two-speed transfer case, locking rear differential, Rancho monotube shock absorbers designed specifically for off-roading, along with skid plates and 18- or 20-inch alloy wheels fitted with all-terrain tires or optional, mud-loving Goodyear Wrangler Duratecs. Hill descent control and GMC's Traction Select system are also standard. The latter of these two lets the driver choose between preset drive modes, suitable for various types of terrain and weather conditions. The system then adjusts throttle response, shift points, and the electronic stability control according to each mode. Related: 2018 GMC Sierra 1500 buying guide "The 2019 Sierra AT4 is designed for the customer who wants an elevated presence on the road and the capability to venture off life's beaten path," said Duncan Aldred, vice president of Global GMC. "It's also the beginning for the AT4 brand, which will be seen on every vehicle in our lineup in the next two years." Based on the new 2019 Chevrolet Silverado, the GMC Sierra (including the AT4 model) looks to stand out from its corporate cousin in terms luxury touches, along with some subtle exterior details. For the AT4, these visible differences include a body color grill surround and bumpers. Meanwhile, the inner grille, front fog-lights and faux fender vents feature a black-chrome finish. It's not flashy, which is probably exactly what GMC wanted for its upscale truck. The standard engine is a 5.3-liter V8, though buyers can choose an optional 3.0-liter turbo-diesel inline-six or 6.2-liter V8.

Chevy's 6.6-liter Duramax is pretty much all new

To say there's a heated battle in heavy-duty pickups is an understatement, with Chevrolet, Ford, and Ram constantly trading blows of increased torque, horsepower, and towing capacity. The latest salvo is the revised, more powerful turbo diesel 6.6-liter Duramax V8 in the 2017 Chevy Silverado. It has 910 pound-feet of torque, an increase of 145, putting it nearly level with the Ford Super Duty. Here's a closer look at where those gains come from. How exactly did Chevrolet add all that torque plus 48 horsepower? The automaker essentially took a fine-tooth comb to the entire engine. Chevy says it changed 90 percent of the V8, and the cumulative effect of those small changes adds up to big increases. As you might guess, the turbocharger is updated. The larger unit features electric actuation of the variable nozzle turbine (VNT), and what Chevy calls a double axle cartridge mechanism that separates the VNT moving parts from the housing. That helps with heat performance as well, with a claim that the exhaust side of the turbo can run continuously up to 1,436 degrees Fahrenheit. Helping that cause are six exhaust gaskets made of Inconel - an nickel alloy that contains chromium and iron – and upgraded stainless steel for the exhaust manifold. Despite having the same cast iron cylinder block, albeit with some minor enhancements, the engine has new cylinder heads, pistons, piston pins, connecting rods, and crankshaft, which have all been upgraded to handle 20 percent higher cylinder pressures. Alongside the increase in pressure, Chevrolet also increased the cylinder head's structure with a honeycomb design. The pattern features high-strength aluminum with dual layer water jackets that not only improve strength, but also optimize water flow for better cooling. For 2017, the cylinder head also benefits from integrated plenum that aids the engine in getting more air under heavy loads. The cylinder head isn't the only component to get a minor update, as the pistons have a larger diameter pin for improved oil flow. The same detailed improvements has been bestowed to the humble connecting rods (second in our hearts only to the inanimate carbon rod). The new design has the bolts oriented roughly 45-degrees to the rod instead of parallel. The angle split design, as it's called allows for easier passage through the cylinder.

GM mulling off-road variants of fullsize SUVs

According to General Motors, owners "just love off-roading with [its fullsize body-on-frame sport utility vehicles]," namely the 2015 Chevrolet Tahoe and Suburban and GMC Yukon. If that's the case, it's a bit odd that sales of the previous generation of these models with the Z71 off-road package didn't sell particularly well.
Perhaps, considering this disconnect between owner's thoughts and desires with actual sales, it's not surprising that General Motors is reportedly "considering" an off-road specific model. That means the package would include styling changes and badges along with suspension modifications and larger wheels with appropriately sized fender flares.
There's no indication if the off-road model would be called Z71 or when it may potentially go on sale, assuming it ever goes on sale at all.