Specifications of GMC Sierra 3500HD HD Double Cab Long Box 3500 6.6 TD V8 (445 HP) 4WD DRW Automatic

General characteristics of GMC Sierra 3500HD HD Double Cab Long Box 3500 6.6 TD V8 (445 HP) 4WD DRW Automatic

For 2020, the Sierra 3500HD received an all-new 6.6-liter gas V8 engine, which produces a stout 401 hp and 464 lb-ft of torque available from 4,000 rpm. Power is sent to the rear or all four wheels depending on the drivetrain configuration. The new V8 gets the job done, but needs to rev out before things start going, which is not ideal for towing. If you're serious about towing, then you'll have to go for the 6.6-liter Duramax turbodiesel V8 engine, it cranks out 445 hp and a mammoth 910 lb-ft of torque available from only 1,600 rpm. Diesel-powered trucks come with a ten-speed auto transmission. With all that torque on tap, the Regular Cab Heavy-Duty Diesel 2WD will tow a maximum of 36,000 lbs off of a gooseneck hitch.

The 3500HD will never be expected to be a canyon carver or track weapon, but those who buy these trucks will expect solid, stable, and predictable handling that won't get upset easily when towing heavy gear. The new Sierra 3500HD feels comfortable and unhindered when cruising around town, and out on the highway it feels planted, especially when you've got dual tires on the back. GMC's ProGrade trailering system and digital variable steering assist, which automatically adjusts steering weight and responsiveness based on road conditions and speed, help keep things in check when there's a heavy load in the back. Diesel trucks get exhaust braking, which assists in downhill speed-moderation. 

The EPA doesn't require gas mileage estimates for full-size trucks such as the Sierra, but you can expect to see figures ranging from the low to high teens depending on cab, bed, engine, and drivetrain configuration.

There's no doubt that the 3500HD is an intimidatingly large truck, but does its size mean lots of interior space? Front headroom measures around 43 inches and front legroom comes in at an impressive 44.53 inches. That's more than enough for even the largest of drivers. Headroom in the second row is just above or below 40 inches, depending on cab choice, which is still pretty impressive. The second-row legroom remains generous at 43.4 inches in the Crew Cab, although things get a lot tighter in the Double Cab which offers only 35.24 inches.

Buyers can choose between standard and long-bed configurations. Standard beds are 82.2 inches long when measured along the floor, while long beds measure 98.27 inches. Bed width is 71.4 inches across the range, shrinking to between 50.55 and 51.85 inches between the wheel housings. Total cargo volume for standard bed trucks is 69.5 cubic feet, while long bed trucks offer 83.5 cubes. If you're wondering exactly how much stuff you can put on the back, the answer is anywhere between 4,013 lbs and a massive 7,442 lbs.

Inside there's a large center console storage box, glove box, door pockets, and cupholders. The 2021 Sierra 3500HD will carry all of your stuff, and then some.