GMC Sierra 1500 Duramax: What the Full-Size Family Car Should Be?

The full-size pickup is the new big family sedan, and it has been for a few years now. And you could probably call the full-size SUV the new family wagon. But can the new family sedan do everything that the old family sedan could? I took the GMC Sierra 1500 AT4 Duramax on vacation to find out.

We had planned to leave the country for a vacation this year, but the ‘rona has made sure we can barely go to the next province over. So a staycation, somewhere nice and remote and quiet (and without internet access) was in the cards. As was the Duramax diesel Sierra 1500. So we loaded up the modern family truckster for a week at a remote lakeside cabin with two people and a dog that needs more exercicse than a four-year-old on meth to find an answer to that question up top.

It started out with a big yes and a big no.

The CarbonPro bed has loads of space to hold your supplies, including the dog’s crate that I wouldn’t have even needed to fold were it not too wide to fit through the house doors. With the bedsides widened for the new generation, there was lots of volume, and the MultiPro tailgate is magic for loading.

Even at well over six-feet, modern truck beds are so high that jumping in and out is awkward and painful. The easy step makes hopping in a breeze (along with the handy handle) and so loading everything took no longer than it would have in a sedan. Maybe less time, since the space is so open.

But the problem with the big trunk of the pickup compared with the one in the family sedan is that it doesn’t close. The weather, meanwhile decided that we would be packing in the tail-end of a literal hurricane. The two don’t mix.

Can you fix that problem? Sure, with a soft or hard tonneau cover for an extra few grand, or, if you’re not keeping the truck, or have tall stuff, you use some plastic tubs, tarps, and straps. Three easy to reach tie-downs in each front bed corner and a pair in the center-front make that easy, along with more at the open-end of the bed. While they were at it with the hooks, though, two more mounted above the wheel wells would have made stapping down a tarp for a highway drive a whole lot easier.

AT4 means a couple of inches of lift over standard, which is handy if you’re taking your family sedan rock-crawling, but my wife and my dog both say to skip it. Get a well-optioned SLT or deal with the flash of a Denali instead for easy access. Family sedans don’t need to rock climb, they just need to make it down the gravel road to the lake.

While the AT4’s lift, all-terrain rubber, and off-road-tuned Rancho shocks were great on the half-mile roughed-out path to the lake, and were wonderful on the low maintenance dirt roads, the pure-pavement ride was floaty, imprecise, and, well, once we were on twisty rural highways it really slowed us down. Yellow speed signs became more than just suggestions. There’s a lot of mass to dampen here, and it showed by way of a highway ride that somehow felt as bumpy on smooth pavement as it did on potholed craters. So if you plan on using the off-road and rough-road capability it’s great. For everyone else, it’s a pass and you might want to pack some of the commodious cabin cubbies with some of those airline bags for your passenger.

At lower speeds, it was handy, though. Thanks to the 800,000 or so camera views, I was able to back right up to the deck and take a small step into the bed rather than up onto it. With the rain, though, the suitcases had to live in the back of the cab instead of the bed. That’s a big space, but it can’t do suitcases and passengers at the same time, so mark one down on the family sedan points tally.

We didn’t need to bring a boat with us, thanks to the kayaks already present at the cottage, but had we needed to, the Sierra is ready to tow a boat as big as you could need. With a built-in brake controller, trailer memory, a plug to add cameras to the trailer, and a million other seriously useful trailering features to make it easy. Would the family sedan haul a trailer? Yes. This well? Heck no. Point: truck.

One of the things that pickups have long had in common with 1970s family sedans was fuel economy. Sure they’ve gotten a touch better over the years, but if you top 20 mpg in a full-sizer you’re either driving downhill with the wind behind you or you’re hypermiling and driving everywhere at 45 mph. Heck, the last Tundra I had barely broke into the double-digits, and I do hypermile.

Not so in this Duramax, which has the award for the second-best fuel economy I’ve ever seen in a pickup. What beat it? A Canyon with the smaller Duramax diesel. It’s nothing short of astounding watching the total range show more than 600 miles after a fill-up, then seeing the average MPG gauge tick above 26. That’s right, 26 mpg. On 65 mph hilly rural highways (read loads of braking and plenty of accelerating) with a thousand pounds of stuff in the back. With a lift and big chunky tires. A non AT4 with more efficient tires should make 30 a breeze, with the same for the flatter, straighter highways of most of North America. On the fuel economy charts, this truck handily beats even the upcoming F-150 Hybrid for both highway and combined fuel economy, and it’s not that far off in town either.

There’s more to just fuel economy, of course, and you’ll have to pardon me while I go on about this engine for a while, because right now it’s one of my favorite drivelines of any vehicle short of a sports car. The inline engine has long been known for smoothness, and this three-liter six is no different. Can you tell it’s a diesel while it’s running? Sure, I guess, especially if you have the windows down, but it’s quieter than any gas truck. And you want a tiny bit of clatter anyway, it’s part of the character.

277 hp and 460 lb-ft of torque mixed with the 10-speed auto make it feel quicker than the other diesels (the HD’s tenner does the same to make the 3500 HD 6.6L Sierra feel massively quicker and more agile than the 1,000 lb-ft Ram brags about with just six gears), and if this doesn’t accelerate quickly enough for you then you probably won’t be happy in anything with a box short of that upcoming Hummer EV.

I know that some states charge more for diesel than gas, but using half of what a gas truck would should more than make up for the pain. Especially now that GM is slashing diesel prices for 2021 meaning that this is cheaper than the 6.2 by a large margin. Here, diesel is much cheaper for most of the year, saving you even more. And even if you’re spending a bit more, using less fuel reduces your carbon footprint and with half of all sales being trucks these days, that’s more important than ever. Hey, nobody said you couldn’t be eco-sensitive and still own a truck, that’s just silly talk. Especially to tide you over until the electric trucks arrive.

The cabin of the Sierra makes it a great long-distance drive, though the AT4 suspension, and I won’t dwell on this anymore, is not your highway friend. Massive, comfortable seats, minivan levels of cupholders, and a rear seat with more legroom than a first-class airline seat (remember air travel?) mean that you won’t be able to hear the “are we there yet” cries because they’re too far away from you to notice. The center console, in addition to having no fewer than five cupholders, also boasts enough space for you to grow an entire tree. No really, we brought one along, dubbed the CarbonsaiPro.

GMC’s infotainment system is one of the best for looks, function, and responsiveness, but it’s a shame the 8.0-inch screen looks so tiny in the dash. A larger portrait-style one, or maybe even a double-stack screen so you could have, say, trailer views and nav at the same time would be a game-changer here. It’s loaded with old-school buttons and dials to control everything important, which we love. However, the buttons are on the cheap side, as is the plastic around them, and every Sierra we’ve driven so far with heated seats felt like the buttons were about to fall into the dash. It’s a shame on an otherwise very well designed and engineered truck. Then again, the old family sedan wasn’t always much better; I remember my parents trading in a five year old box-Impala because, among other problems, the door-mounted armrests had all fallen off.

So does the Sierra handle the work of the full-size family sedan? It does, and it does with ease. As long as you get a tonneau cover.

The diesel is smooth, silent, and can pound out hundreds of miles of highway in one go. The back seat has room for you to stuff five friends like you would have back in high school (Please don’t, and always wear your seatbelt! -Ed.), you can put literal bales worth of cargo in it for the weekend, and you can tow just about anything short of a house. What can’t it do? Well, it can’t keep your stuff dry, just about every feature you want (like radar cruise) is on the options list no matter which trim you pick, and you had best make damn sure you’re going to spend all your time off-road before you tick the box marked AT4. Spend some time in this rig and it’s not hard to see why they’re so popular, and spend time with the diesel and feel a lot less guilty about not using all of the capability all of the time.

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