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2015 Chevrolet Silverado GMC Sierra HD - First Drive

Posted in Vehicle Reviews on April 14, 2014 Comment (0)
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2015 Chevrolet Silverado GMC Sierra HD - First Drive

GM’s biggest truck buzz for 2015 is the new Colorado/Canyon. Until those models appear, the facelifted ’15 HD pickups—Silverado and Sierra 2500 and 3500—give truck enthusiasts something new to get excited about.

Visually, the HDs now have the 1500 trucks’ broad-shouldered stance and bolder grille. The mechanicals carry over, though. GM’s HD engineering was primarily in air-management: directing airflow through and around the new front clip to maximize powertrain cooling while tightening gaps to minimize aerodynamic drag.

In the process, powertrain software was recalibrated to capitalize on the improved cooling. This tuning is partially responsible for higher towing and payload ratings from the existing hardware. (Since the automakers can’t agree on standard tests, specs appear to be compromises between each manufacturer’s engineering, marketing, and legal departments.)

Max payload rating is now touted as a class-leading 7,374, (C3500 regular cab longbed 6.0L Vortec dualie) with fifth-wheel max trailer towing of 23,000 pounds (K3500 regular cab longbed Duramax dualie). Conventional hitch-towing is rated best in class at 19,600 (K3500 Duramax dualie). Of the higher-volume configurations, the Crew Cab longbed K2500 gas is rated at a 3,388 payload/13,800 fifth-wheel trailering; diesel is 2,628/16,400.

Most buyers will choose the Duramax option (1.5 million served to date). GM rates the Duramax/Allison combo for 200,000 “rough duty” miles. The venerable Vortec 6.0L V-8 comes in the L96 gas/E85 package or LC8 CNG bi-fuel configuration. CNG drops output ratings by 59 hp and 47 lb-ft. Most buyers will choose the Duramax option (1.5 million served to date). GM rates the Duramax/Allison combo for 200,000 “rough duty” miles. The venerable Vortec 6.0L V-8 comes in the L96 gas/E85 package or LC8 CNG bi-fuel configuration. CNG drops output ratings by 59 hp and 47 lb-ft.

Although the 2015 Silverado/Sierra is outspec’d on paper by the competition in some columns, GM’s new powertrain programming sends a high percentage of the available power to the ground. Towing 10,000-pound trailers, a K2500 Duramax Silverado accelerated faster up a 6-percent grade than similarly equipped competitors. GM’s tuning seems more aggressive: Possibly more boost and higher shift points allowed the Chevy to pull away from the others during these uphill tow-offs.

But the biggest differences were downhill. The 2015 Chevy Silverado K2500 maintained cruise control speed with only minor fluctuations. The 6.6L Duramax and six-speed Allison 1000 automatic work in sync with the exhaust brake and Tow/Haul mode to modulate transmission shifting and engine backpressure (regulated by the variable-vane turbocharger). The similarly outfitted competitors’ trucks surged ahead in side-by-side cruise-control comparisons while descending the same grade. The 2015 Chevy Silverado never required brake-pedal application. The overall feel is more control; less brake-component wear is a beneficial side effect.

The enduring Z71 off-road package offers two tiers. The suspension group includes skidplates and upgraded shocks. The Z71 appearance bundle starts with the suspension components and adds a body-colored front bumper, all-terrain tires, foglamps, and decals/badges. The enduring Z71 off-road package offers two tiers. The suspension group includes skidplates and upgraded shocks. The Z71 appearance bundle starts with the suspension components and adds a body-colored front bumper, all-terrain tires, foglamps, and decals/badges.

Another software upgrade is StabiliTrak traction control, now standard on the HD trucks. Trailer Sway Control is also part of the package. If the tail starts to wag the dog, this system automatically applies the wheel and/or trailer brakes as required to get the tandem back in line. The ’15s also have an available dash-mounted trailer brake control.

Underneath, the tried and true torsion-bar IFS with rear leaf springs are tuned for a smooth road ride. The torsion bars also allow some ride height adjustment to accommodate snowplows, aftermarket front bumpers, and other stance-altering accessories. The asymmetrical leaf springs are designed to support loads while controlling wheelhop.

To ease access, the rear bumper gets the 2015 Chevy Silverado 1500’s built-in corner steps and the dualie models have available flip-down sidesteps at the front of the box. The 1500’s popular “EZ” tailgate is now standard on higher-trim models. This system uses an interior torsion bar and damper to ease lifting and lowering.

Also new is front-hinged doors on Double Cab models, part of a stiffer overall cabin, which is softened by hydraulic body mounts. Like the 2015 Chevy Silverado 1500, the HDs’ doors are inlaid under the roof. This, plus triple sealing, makes the cab noticeably quieter. Normal conversation is possible with backseat passengers, even with the Duramax turning 3,000 rpm while climbing a grade.

Mechanicals are “same old, same old,” but styling and tech take steps forward. The Denali interior features a lot of leather, an 8-inch touchscreen monitor, up to five USB ports, four 12-volt outlets, an SD card slot, and a 110-volt AC outlet. OnStar will offer 4G mobile Wi-Fi hotspot capability this fall. 
Mechanicals are “same old, same old,” but styling and tech take steps forward. The Denali interior features a lot of leather, an 8-inch touchscreen monitor, up to five USB ports, four 12-volt outlets, an SD card slot, and a 110-volt AC outlet. OnStar will offer 4G mobile Wi-Fi hotspot capability this fall.

Too Many Choices?
GM hopes to have something for every new-truck shopper who hauls and tows. More than 150 configurations are possible between Silverado, Sierra, gas, diesel, bi-fuel, 3⁄4-ton, 1-ton, cab and bed lengths, trim levels, tire/wheel combinations, and so on.

Trimwise, the 2015 Chevy Silverado does offer a stripped down Work Truck (WT) level, which is available only as a regular cab but can also be ordered as cab/chassis for the commercial market. The two other trims are LT and four-door-only LTZ. GMC Sierra models offer more amenities at each level. The three trims are SLE and SLT and the posh Denali, which is crew cab only. Denali is characterized by brightwork inside and out, LED daytime running lights, a leather interior, and a standard 8-inch touchscreen infotainment monitor backed by a Bose stereo system.

For 4-wheelers who want to tow their toys to remote areas, the Z71 Off-Road package is offered in Silverado SLE and SLT trims for both 3⁄4- and 1-tons, 4x4 and 4x2. The package includes upgraded shocks (Rancho monotubes in the 2500), jounce bumpers, Hill Descent Control, and skidplates. The enduring Eaton “G80” rear limited-slip is still available.

Further, the new HDs offer an OEM spray-in bedliner checkbox. Other available accessories include running boards, underrail LED bed lighting, and a tonneau cover.

High-rolling ranchers who want it all can easily get the MSRP over $70,000 by fully optioning a K3500 Denali dually—basically a long-wheelbase luxury sedan that can haul concrete and cattle.

The HD bar will undoubtedly raise higher this year when the ’15 Super Duty is released. Then, GM will need to start reloading for the next round of HD torque wars.

Specifications
2015 GM Silverado/Sierra HD 4x4
MSRP Range $31,310-$70,000+

Drivetrain
Engines 6.0L Vortec L96 V-8; 6.6L Duramax LML V-8 diesel
Horsepower 240 @ 5,400 rpm (gas); 397 @ 3,000 (diesel)
Torque (lb-ft) 380 @ 4,200 (gas); 765 @ 1,600 (diesel)
Transmissions 6L90E 6-speed automatic (gas); Allison 1000 6-speed automatic (diesel)
Transfer Case/Low-Range Ratio MP1626/2.72:1

Suspension
Front Unequal-length A-arms, torsion bars
Rear 2-stage multileaf springs
Tires LT245/75R17, LT265/70R17, LT265/70R18, LT265/70R18, LT265/60R20 all season/all-terrain
Wheels 17x7.5, 18x8 steel; 17x7.5, 18x8, 20x8.5 aluminum

Dimensions
Overall Lengths (in) 224.4-258.4
Wheelbases (in) 133.6, 144.2, 153.7, 158.1, 167.7
Overall Heights (in) 77.7-78.2
Overall Widths (in) 80.1-80.5
Min. Ground Clearance (in) 8.2
Curb Weights (lb) 6,044-7,777
Max. Payload Capacity (lb) 7,374
Max. Tow Capacity (lb) 19,600 (trailer), 23,200 (5th wheel)
Fuel Economy (city/hwy mpg) TBD

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