2015 GMC Sierra Denali HD First Test
The Broadest-Shouldered Butler Since Lurch
All done up in black and chrome, the new Sierra Denali HD looks like it's wearing a tuxedo, but its burly stance and jacked suspension suggest it plans to work whatever formal event you have in mind. Indeed, when it arrived at our shop, we put it right to work. Its first task was to make a 360-mile run that included ascending the Davis Dam's 12-mile, 6-percent grade while carrying a ton of horse-stall mats in the bed. (Our Duramax crew cab 4x4 truck's 10,000-pound gross vehicle weight left 271 pounds for payload, so our lone driver and his social-media connectivity gear weighed in well within spec.) Our test equipment kept a watchful eye out for signs of laziness during the hill-climb event. We then hitched a 5-ton trailer to its Class IV receiver hitch and gave it another workout. (It's rated to tow 13,000 pounds off the back, 17,100 with a gooseneck or fifth-wheel hitch.).
As with all heavy-duty pickup trucks, this one feels a bit jittery and uncomfortable riding around empty. It jounces with the nervous energy of a track star who longs to be running. L.A.'s infamous tilted slabs turn freeway rides into a hobbyhorse experience when a truck is empty, but stick a ton in the back, and this giant manservant gets right to work pummeling the road into submission. Beyond the ride improvement, the drivability, acceleration, and braking performance didn't feel noticeably degraded by the burden, though it must be noted that the Allison transmission is programmed to favor the highest possible gear selection, which can make the truck feel a bit lethargic compared with certain competitors (cough, F-Series SuperDuty).
The GMC Sierra HD is a 2015 Motor Trend Truck of the Year contender - find out before long whether it has what it takes to win.
Once on the Davis Dam, we conducted a "Frustration Test" that simulates being stuck behind some wanker going 50 in a 65-mph zone then fire-walling the go-pedal and accelerating to 70 mph to pass. The test was conducted numerous times, with the transmission's tow/haul mode engaged and disengaged, and we found it made no difference in this test, which took 8.9 seconds and 773 feet either way. That's roughly double the 45-65-mph rolling-acceleration rate required when the truck is empty and on level ground at low altitude (not that the latter makes much difference to this turbocharged oil-burner). Descending the grade, we were impressed with the way the cruise control integrates with the diesel exhaust brake to maintain a steady downhill speed, even when loaded.
Next we hitched up a hefty 10,000-pound trailer. This it noticed. A lot. There was significant turbo lag off the line, and all acceleration times doubled or tripled from a quite reasonable 7.7 seconds to 60 mph and 16.0 seconds at 86.4 mph empty to a still-respectable 19.8 and 22.0 at 62.7 dragging the trailer. The tow/haul mode did make the rig accelerate a bit quicker in this case, altering the shift schedule slightly. Fun fact: Tow/haul mode also doubles the flash-to-pass feature's number of turn-signal blinks to six.
We feel that trailers this heavy are probably best towed with a gooseneck or fifth-wheel, which simplifies maneuverability. (Reversing a long truck with a long rear overhang and a hitch behind the bumper is way trickier than reversing a gooseneck.) Bumps upset the rig more with the bumper-style hitch, as well, and handling generally seems to suffer considerably (though the StabiliTrak system now includes standard trailer-sway control). And while the reverse camera gives a good view of the hitch area, its low resolution and lack of a trailer-hitch alignment line (as the competition offers) made it difficult to place the truck in precisely the right spot to lower the trailer tongue onto the ball the first time without a spotter.
As the chaperone of our long-term Sierra Denali, a 1500-series 5.3-liter doppelganger for this truck, I felt completely at home in the roomy, well-appointed, attractive interior, and I was impressed by this one's upgrades. These include the new-for-2015 4G-LTE Wi-Fi hot spot, the off-road inclinometer, and dash screens for engine-on and idle hours and diesel exhaust fluid level. The collision warning system is another welcome addition that doesn't seem too "nervous," and the vibrating "safety-seat" lane-departure warning system is useful in any vehicle that consumes this much of a lane. (It should be mandatory standard equipment on dualies.)
Sure, you could save a fair chunk of change by purchasing the exact same functionality with a Chevy bow tie on the nose, just as you could easily employ a personal assistant in khakis and an Oxford button-down. The Sierra Denali is for folks who prefer a broad-shouldered butler.
|2015 GMC Sierra Denali HD (2500 4x4)|
|PRICE AS TESTED||$65,235|
|VEHICLE LAYOUT||Front-engine, 4WD, 5-pass, 4-door truck|
|ENGINE||6.6L/397-hp/765-lb-ft turbodiesel OHV 32-valve V-8|
|CURB WEIGHT (F/R DIST)||7,729 lb (60/40%)|
|LENGTH x WIDTH x HEIGHT||258.3 x 80.5 x 77.9 in|
|0-60 MPH||7.7 sec|
|QUARTER MILE||16.0 sec @ 86.4 mph|
|BRAKING, 60-0 MPH||154 ft|
|LATERAL ACCELERATION||0.72 g (avg)|
|MT FIGURE EIGHT||29.7 sec @ 0.75 g (avg)|
|EPA CITY/HWY/COMB FUEL ECON||Not rated|