The 6.6-liter gas V8 does a great job of moving you along when you aren’t towing and climbing. The engine is mated to a six-speed 6L90 transmission, which handles the power and torque of the gas engine well and shifts smoothly. While towing, and on an incline at altitude, it’s obvious that the naturally aspirated V8 was down on power and wasn’t enjoying climbing up a mountain road hauling a skid steer. While it wasn’t happy, the gas engine didn’t overheat or produce any catastrophic hiccups: It just had to deal with thinning air, which is a problem any naturally aspirated engine faces at altitude.
The diesel-burning Duramax, however, didn’t mind the altitude all too much. Making 445 hp and 910 lb-ft of torque, the turbocharged Duramax pulled 12,000 pounds up a hill with authority. You could feel the weight, but the Duramax kept churning along and could still accelerate despite the circumstances. Mated to the carryover diesel engine is the new for ’20 Allison 10-speed automatic transmission. While towing, the transmission helps keep the Duramax’s revs down and torque up. It also helps you better manage your speed while engine braking by giving you a wider gear spread to help better control your desired speed without having to hop on the traditional brakes every few seconds. That gives the 14-inch brake rotors on all four corners a chance to cool off to help keep fade to a minimum.
Without anything behind the Silverado HD 2500, the new Allison transmission is smooth and uneventful: ideal for heavy-duty transmissions. Violent shifts might be fun in a sports car, but the smooth-shifting Allison changes gears quickly and doesn’t upset the cabin in the process.
The new towing camera system does exactly what it’s supposed to do: inspire confidence. The side-view cameras feed a stream of nonstop trailer wheels to your dash-mounted touchscreen. Sure, you can use the blind spot mirrors to spot your trailer, too, but it’s nice having the extra eyes on your trailer if you’re not hauling something every day. The invisible trailer feature is kind of gimmicky while in motion but pays dividends when backing up.