2015 GMC Sierra 2500HD Crew Cab Denali 4×4 review: Six-point-six liters worth of big

2015 GMC Sierra 2500HD Denali

2015 GMC Sierra 2500HD Denali

Here’s a surprise, not. The 2015 GMC Sierra Denali 2500HD 4WD Crew Cab is big. It’s big even with the “short” six-and-a-half foot bed—an eight-footer is available. The “short” bed’s wheelbase 153.7 inches. For perspective, a Chevrolet Spark is 144.7 inches one end to the other.

And while we’re at it, the name is long, too, typical of pickup trucks, but here’s how this one breaks down. “Sierra” is GMC’s generic name for a pickup truck, whether a “half-ton” 1500 or a heavy duty, such as our test 2500, or the even stouter 3500. “Denali” is the fanciest trim, a lineup that starts with a nameless base model, then up through the midrange SLE and SLT.

2015 GMC Sierra 2500HD Denali grille

The 2015 GMC Sierra 2500HD Denali has a chrome grille and body-color bumpers. (click to enlarge)

The cab range runs from standard, with two doors not much room behind the one row of seats, to double cab (replacing an “extended cab,” with rear-hinged doors and inside-only handles), with four doors and an occasional second row seat, and to crew cab, with longer rear doors and room for three adult males, if a bit of squeeze on the shoulders.

And of course 2WD vs. 4WD. No need to mention that 2WD is the rear wheels, while 4WD models can be operated on most economical two-wheel drive, automatic four-wheel (all-wheel) drive, and four-wheel center differential locked, and four-wheel low range.

2015 GMC Sierra 2500HD Denali hood badge

A badge identifying the 2015 GMC Sierra 2500HD Denali as having the 6.6-liter Duramax turbodiesel. (click to enlarge)

Engine choices for the 2015 Sierra 2500HD include a 6.0-liter V-8 engine with either gasoline or gasoline/natural gas fuel, and, the subject of our review, a 6.6-liter turbo-diesel. This is a case where 6.6 equals 765. That’s 765 lb-ft of torque. That’s enough, with a trailer hitch on your house, you could take it camping with you, and that’s even if your house didn’t originally come with wheels.

It’s not the first heavy-duty pickup, of course, with a tow rating measurable in tons, note the plural. GMC claims 13,000 lbs for the crew cab with the 6’6” bed (with either engine, actually). Doing the math for you, that’s six-and-a-half tons with a ball-hitch. Have some horses to ride somewhere you don’t want to ride them to? A goose-neck trailer hitch brings the max tow rating to 17,100 lbs.

2015 GMC Sierra 2500HD Denali interior

The 2015 GMC Sierra 2500HD Denali interior is well equipped. (click to enlarge)

That’s the kind of thing one learns poring over the trailering spec sheet.

Of course, charts and numbers are one thing and driving another. And perhaps one becomes accustomed to driving a house like this, but as we said in the beginning, this is a big truck. It’s wide, it has a turning circle measured in ginormous (that’s a real word, you can look it up), and the trailering mirrors make getting close to the drive-up window a definite challenge.

And that latter is made worse by the overall height of the tuck. Not only do you have to reach out, you also have to reach down for the milkshake And please, no whipped cream and cherry. How am I supposed to eat that with a straw? The order-taking person probably couldn’t hear me over the diesel clatter anyway.

And noise, yes, this is a traditional diesel, and unlike the more civilian-friendly diesels, such as the Audi V-6 or the FCA EcoDiesels. On the other hand, those engines aren’t put in HD pickups, either, so ya spends your money and ya take your choices.

2015 GMC Sierra 2500HD Crew Cab Denali

2015 GMC Sierra 2500HD Crew Cab Denali (click to enlarge)

Roll up the windows, however, and it’s not so loud…assuming of course that you’re inside the truck. Seriously, no one will forget this truck is a diesel but the noises are well insulated. But even with a light load, the big diesel acts like a traditional big diesel. The big turbo can be heard spooling up as the torque-meter—if there were such a thing—wraps around the dial. They say that torque equals acceleration? Not here. This torque equals a thundering inexorable mass, but don’t expect to win a lot of truck versus car drag races. Unless both vehicles are hitched to 10,000 lb trailers.

Don’t worry about the transmission, however. The 6.6-liter Duramax turbodiesel V-8 comes with an Allison 6-speed automatic transmission standard.