There's a few more numbers to throw at you before I dive into the driving experience, such as the 21,700-lb towing capacity that the trucks have when equipped with a fifth wheel, and the 17,000-lb conventional towing capacity. Payload stands at 6,635 lbs. The trucks have a 5-year/100,000 mile warranty.
Exact fuel economy numbers weren't given, but GM says that there is an 11 percent improvement over the previous trucks, and that the highway range on the diesel is 680 miles, with the gas engine falling only a bit a shy of that number.
GM says that the diesel won't need an engine-block heater unless the temperature drops below -20 degrees Fahrenheit, and that the glow plugs will take no more than 3 seconds to heat up as long as the mercury is above -20.
Perhaps against the company's better judgment, GM allowed journalists to hop into several different variations of both Silverado and Sierra HD models, including one with a dump truck body. Some trucks were unloaded, some were ballasted, and some were hooked up to trailers. We even got some seat time in the competition's offerings.
Barely an hour after touching down in Baltimore, I found myself nervously taking the wheel of a truck that was towing a 9,000-lb trailer. Thanks to the grades and hills of western Maryland, I'd soon be testing the 6.6-liter diesel's--and the exhaust brake's--capabilities.
Nearly 800-lb feet of torque (for perspective, that's more than double the twist of the most powerful sports cars) gave the 6.6 enough thrust to get rolling. Maybe "fast" isn't the best adjective to use here, but strap a trailer to your back, and see how well you move.
The exhaust brake does its job quietly and competently, slowing the truck enough so that a downshift will kick in, forcing engine speed up and vehicle speed down. It doesn't work alone, however. To bring about said downshift, it's best combined with the cruise control or a brief application of the wheel brakes.
Speaking of brakes, the wheel brakes are smooth and solid, even with the huge trailer tagging along out back. Ride and handling are also impressively smooth when towing.
Unloaded, the truck drives a bit like the GM light-duty trucks, albeit with a higher ride height. Acceleration is a tad slow on both models, due to the mass of the truck, but it's not unacceptable for a truck of this size, nor is it any worse than the Ford or Ram. GM says it that 2500HDs can hit 60 mph in less than 9 seconds and the quarter-mile in under 16 seconds, which is plenty enough acceleration for real-world driving.