Ever since the 2015 Chevrolet Silverado and GMC Sierra HD were first unveiled at the State Fair of Texas last year, we knew both brands’ trucks were going to take on styling similar to that of their ½-ton siblings. We also knew the engines and transmissions weren’t going to change. And now that the new body, interior, and other improvements have come to the HD models, GM has completed the transition to the new generation of HD trucks. You can consider this the end of the GMT900 trucks and the start of the K2s.

As was the case before, both the ¾- and 1-ton pickups come with a choice of a 360-hp, 6.0-liter gas V-8 and Hydra-Matic 6L90 or a 397-hp, 6.6-liter Duramax turbodiesel V-8 and Allison 1000. Both transmissions are six-speed automatics. Why didn’t GM change the powertrains? As Jeff Luke, executive chief engineer on the trucks, explained, the HD models were all-new under the skin for 2011. It was during that significant update that these trucks got fully boxed frames with high-strength steel. (Unfortunately, the DEF refill spot is carryover -- it’s still hard to reach, as it is all the way against the firewall in the engine bay. Other manufacturers site it behind the fuel door.) As a side note, we were told the HD frames have essentially nothing in common with the ½-tons’ frames, which were new for 2014.

While the torque -- 380 lb-ft for the gas engine and 765 lb-ft for the diesel -- are not the highest in the class, Chevrolet and GMC aren’t worried about it. Their goal with the HDs was to make the power easier to use than before and make the trucks more capable of hard work. The idea is to ensure that people can use their trucks for hard work with confidence, and to make the trucks easier to use on the job and on the weekend. These were a higher priority than winning the specs battle.

Our first opportunity to try the new trucks was at a recent drive event in Arizona. The location GM chose made it easier to drive vehicles unloaded, loaded with payload, and towing, all from a central location. All the trucks at the event were crew cabs, and it was apparent that the styling on the GMC and the Chevrolet HDs is similar to that of the ½-tons: the Chevrolet is more conservative and classic while the Sierra HD looks ready for city life. But the commonalities with the ½-tons don’t end there: The new HDs get CornerSteps on either side of the bumper and the optional EZ Lift-and-Lower tailgate.

The new body brought more than just new styling. The all-new exterior is now made with generous amounts (2/3 of the cab, for example) of high-strength steel, helping make the body is stiffer. And as is the case with the ½-ton Silverado and Sierra, the extended cab has been dropped, and the HD trucks now come as regular, double, or crew cabs. The HDs will come with a 6-foot-6 or 8-foot bed.

For the drive route, we began in a 2500 Sierra HD, a Jet Black four-wheel-drive Denali crew cab. It had a Duramax under the hood and rode on 20s. Not all the boxes were checked, but this truck’s as-tested price was $65,840. We noted that the crew cab’s front-seat legroom is essentially the same as before, but now there is more space in back. GM is using new seat filler material that makes the seats thinner without affecting comfort. They also changed the angle of the front seats. That combination adds 2 inches of rear-seat leg- and kneeroom.

The cabin, which once looked outdated, has leapt far forward and looks a lot like the ½-ton’s interior. It has amenities like the 8-inch screen in the center stack, MyLink and IntelliLink, and easy touch-screen access to the navigation system and entertainment options. Chevrolet and GMC will be adding the option of Wi-Fi through OnStar later this year. Material quality is great across the board, but the Denali is a step up from that. A cool touch on the Denali was an LED version of the old-school dash-mounted bubble compass nestled between the gauges in the cluster. The cabin is quiet, too, thanks to triple-sealed, inlaid doors, and hydraulic body mounts.

As with the GMT900 trucks, the Duramax is an excellent engine, quickly pulling the truck to speed from a stop and doing it fairly quietly. Making the cabin quieter risked highlighting any turbodiesel noise, but the turbos and exhaust brake aren’t noisy. When braking, we found the pedal feel firm and the brakes responsive and linear. There were improvements here, too. As engineers explained to us, the brake rotors and calipers are the same as before, but the four-channel, four-corner brake modulator manages the new ABS, stability control, and traction control. Antilock brake efficiency is better as well, and stopping distances are even shorter.

Remember the days when heavy-duty trucks would ride horribly? It was fine at the time, because it was to be expected when you were in something capable of towing that much weight. Not anymore. Heavy-duty trucks are much more refined than they used to be, as was the case in the Silverado and Sierra HDs. Comfort is now an important selling point. The ride was better than we expected. The 2015’s firm ride isn’t as nice as in a ½-ton, but it’s quite comfortable. The front suspension is independent torsion bar, and the rear setup uses asymmetrical leaf springs. Slight changes were made to the suspension geometry to accommodate the new body, but the suspension is carryover otherwise.

We spent the rest of the day driving other Chevrolet and GMC HDs. We took a Silverado 3500HD out that was full of payload, and discovered the truck did very well. As you would expect in this size category, the truck didn’t even feel like it had a massive load in the bed. The Silverado/Sierra HD now has best-in-class payload capacity, at 7374 pounds. We also learned that the new trucks can carry a 100-pound snowplow and up to 1000 pounds of the equipment that goes along with it -- and any 4WD HD is snowplow-ready.

We were also impressed with the amenities and the changes GM made with towing in mind. The team of engineers added a variety of cooling that help ensure reliable towing in hot weather: They gave the truck a sealed front end and made sure the engine’s air intake is isolated from the hot engine bay, keeping the air cooler. There’s more safety equipment and new electronics, too: StabiliTrak with trailer sway control is now standard on all models, including dualies. We noted cool features such as hill start assist and hill descent control, and, as we discovered when we towed in the Silverado HD with the Duramax, the cruise control is integrated with the exhaust brake and auto grade braking. That makes it easier to keep a consistent speed when towing up and down steep hills. Conventional and fifth-wheel towing capacities are increased for 2015: Maximum capacities are 19,600 (up from 18,000) and 23,200 pounds (up from 22,500), respectively. Another feature GM added was a new hitch receiver rated for 20,000 pounds. That makes it possible to conventionally tow up to 19,600 pounds. In addition, the 2015 uses more cooling,

With trucks that are used for work, the driver doesn’t want to think about whether or not the vehicle is going to do everything expected of it. It’s like owning a hammer. You want the hammer to do what’s asked of it without having to wonder if the head is going to stay on the handle. GM has made sure the Silverado and Sierra HDs give drivers that sense of confidence, that they won’t have to worry about their truck while it’s on the job. It would’ve been nice to see some more horsepower or torque come from the engines in the trucks, but the engineers have done a great job getting the best use possible of the power that’s available. We wonder about a few other things with the new HDs, though. Will there be 4500 and 5500 versions? It would make sense, since GM is currently the only member of the Big Three not in that segment. Also, will there be a Chevrolet High Country Silverado HD? That move would also make sense.

GM has already started production at the Ft. Wayne, Indiana, and Flint, Michigan, plants, and the truck is currently on sale.


2015 GMC Sierra Denali 2500 4WD Crew Cab
BASE PRICE $54,835
PRICE AS TESTED $65,840
VEHICLE LAYOUT Front-engine, 4WD, 5-pass, 4-door truck
ENGINE 6.6L/397-hp/765-lb-ft turbodiesel OHV V-8
TRANSMISSION 6-speed automatic
CURB WEIGHT 7384 lb (mfr)
WHEELBASE 153.7 in
LENGTH x WIDTH x HEIGHT 239.5 x 80.5 x 78.2 in
0-60 MPH 7.7 sec (est)
EPA CITY/HWY FUEL ECON Not rated