GMC bills the new Sierra HD as the most capable heavy-duty truck it's ever built and promises a world-class towing experience. Considering how heavy the competition is from Ford and Ram, those are some serious claims. But to back them up, GMC chose to launch the Sierra HD with a Duramax 6.6-liter turbodiesel with a new 10-speed Allison automatic transmission.

That engine is good for 445 hp and 910 lb-ft of torque. Maximum towing capacity hasn't been finalized yet, but GMC claims it will be "well in excess of 30,000 pounds." For comparison, the most powerful diesel Ram HD now makes 400 hp and 1,000 lb-ft, and it's rated to tow up to 35,100 pounds in 3500HD dually form. GMC says it will also announce an optional all-new gas engine soon.

Like it did with the light-duty Sierra, designers worked to give the Sierra HD a look that further distinguishes it from its Chevrolet counterpart. We'd say the new front end looks more grumpy than rugged and tough, but you certainly won't mistake it for the Silverado HD. Then again, as negative as the reaction has been to the Chevy's new styling, that's probably a good thing.

Since more than half of all Sierra HDs are sold in Denali form, GMC had to up its interior game, too. The end result is a cabin covered in leather, open-pore wood, and aluminum trim. The front seats also offer headroom and legroom that are said to be best in class. And in addition to the touchscreen infotainment system, GMC added a head-up display that it claims is a class first.

You can also now order your Sierra HD with the off-road-focused AT4 package. In addition to some exterior changes and different interior appointments, Sierra HD AT4s all come with an off-road suspension with Rancho shocks, protective skidplates, an Eaton locking rear differential, and 18-inch wheels wearing all-terrain tires. Optional 20-inch wheels are also available. The AT4s also comes with a dedicated off-road mode, hill descent control, hill start assist, and a surround-view camera system.

To make trailering an easier, less stressful experience, GMC gave the Sierra HD the same ProGrade Trailering System found on the light-duty Sierra. Owners can use the surround-view camera system to choose from 15 different angles, and with the available accessory camera in place, the Sierra HD lets the driver virtually see through the trailer. Owners will also be able to download an app that can help them check and prepare their truck for towing.

The 2020 GMC Sierra HD will go on sale later this year, with pricing and final specs announced closer to that time.