• 2017 GMC Sierra HD All-Terrain X First Drive Off-Road Review: New Duramax Diesel Stretches Its Legs

    2017 gmc sierra hd all-terrain x

    The 2017 GMC Sierra HD All-Terrain X is finally here. This is the top off-road package for GMC heavy duty truck lineup. The All-Terrain X package is only available on the 2500-series (aka. 3/4 ton) crew cab Sierras. It uses the Z71 off-road package as the basis. The truck has off-road tuned suspension with Rancho shocks. The blacked-out wheels, the Goodyear Wrangler Duratrac tires, the black grille surround, sidesteps, and the sports/light bar behind the cab add to the truck’s mean attitude. The bed-mounted sports bar is the easiest way to identify the All-Terrain X among all other Sierra HD 4×4 or All-Terrain trucks.

    The All-Terrain X can be had with two engine options: the 6.0L gasoline V8 or the new 6.6L Duramax diesel V8 that you see here. You know it’s the 2017 diesel because of the hood scoop in the hood. The new “L5P” Duramax produces 445 horsepower and 910 lb-ft of torque. It’s still backed up by a 6-speed Allison automatic transmission.

    On the inside, there are extra-cushy leather seats with special inserts and the “all-terrain” logo in the gauge cluster.

    The All-Terrain X has the hardware to backup its off-road credentials. The suspension soaks up rough off-road trails. The big Duramax V8 has more than enough torque to climb steep hills (nearly 20-deg incline during this off-road run). The Duratrac tires work great in nearly every condition. We have tested these tires in the snow and mud on other trucks, and they never seem to lose grip. The transfer case offers 4WD high and low ranges, and the automatically locking rear differential helps out when traction is at a premium. Hill-descent-control is there in case you need help on the way down.

    2016 GMC All Terrain X
    All-Terrain X sports bar

    Not everything is perfect. The All-Terrain X comes standard with the front chin spoiler. It’s removable, but the truck we tested had it installed and it rubbed on some obstacles. The other clearance problem is the now-larger DEF tank that is mounted on the passenger side and protrudes below the frame rail (the tank volume was increased from 5.3 to 7 gallons). The DEF tank has a steel protection skid plate, so chances of damaging the tank are minimized. GM did not get the opportunity to redesign or move the DEF tank for the 2017 model year.

    2017 gmc sierra hd diesel steel skid plate
    DEF tank skid plate

    GM invited TFLtruck (and other journalists) to south-western Colorado for a first drive of the 2017 Sierra HD All-Terrain X and chose the off-road trail for us to use. The truck did not break much of a sweat on this moderate trail. How does it compare against competitor’s off-road heavy trucks? This first drive did not offer the opportunity the push the truck near its limits. Competitor’s trucks were not available for comparison.

    The fully-loaded All-Terrain X you see here has an as-tested price of $69,260 (including destination charges).

    Andre Smirnov
    Andre Smirnov
    Andre Smirnov is an Automotive Enthusiast, Producer, Reviewer, Videographer, Writer, Software Engineer, Husband, Father, and Friend.

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    71 thoughts on “2017 GMC Sierra HD All-Terrain X First Drive Off-Road Review: New Duramax Diesel Stretches Its Legs

    1. Be honest, did it have the same punishing ride once off the pavement that has characterized GM trucks for the last 3 decades?

      In oil and gas work, Ford and Ram dominate, primarily it would seem, because they are liveable on poor roads. The duramax trucks are popular with those who run highways only

      1. GM’s have always had a better ride than Ford’s. Only after Dodge/Ram went to the rear coil suspension did they have a better ride. The Ram also has the softest suspension and lowest payload/towing.

        In HD’s, the GM’s have the best ride due to a lack of a solid front axle.

        So what exactly are you talking about? Have you driven any of the HD trucks? The Ford HD trucks and Rams are popular because of how durable and cheap the solid front axle is, which rides terribly.

        1. Can’t edit, was talking about half tons in the first paragraph and 3/4 and 1 tons in the second. GM has the lowest towing ratings in the 3/4 tons. While always outtowing the Ram which has a higher rating. HMMMMMM

      2. I found the All-Terrain ride quality to be very good. The Duratrac tires, Rancho shocks, and comfy seats combine for great off-road ride.

    2. The sport bar is cheesy looking. Just a bunch of aftermarket parts that you can get directly from GMC at a premium price.

      1. It is cheaper to get them from factory than to buy at a dealer and have the dealer install (it must be dealer installed to have any warranty). Plus factory accessories are covered under the comprehensive 3 yr warranty whereas the same exact accessories through a GM dealer come with one year (and must be installed by the dealer).

        1. All i know is that the trailboss package for the colorado, which seems to be the same stuff(bar, led’s, duratracs, etc) was like an $8000 option. Thats a rip off.

    3. Boy I love GMC, but I hate their marketing… I had to stop watching as the “clown” is describing how black rims and body colored door handles make the package.. but wait there’s more… that substantial rack… really… now the tires are nice.

      1. Totally agree, I mean who do they think they are kidding? And that bar in the bed is just awful. For anyone that actually uses this is a truck all it does is make it harder to get stuff in and out of the front portion of the bed, shades of the Avalanche!

    4. I agree- I also would call myself a GMC fan but that Marketing rep was such a douche!

      I mean I get it- you really don’t have to do anything to these trucks to make them off-road worthy (enough for 99% of buyers). Let’s face it- even in the oil, gas, logging, commercial construction world- no fleet buyer is looking to add qty (50) Raptors, Power Wagons, or $70k Seirra Terrain-X models to there fleet. They look to buy base W/T trim and often even skip the diesel option.

      While there are a few private buyers who will take these off-road, the overwhelming majority will not actually abuse their brand new $70k trucks.

      So while I think GM does a good job of providing more than enough off-road capability for what the market “needs”, the area they continue to avoid is the “want”.

      Perhaps we will see how they (GM & Consumers) respond to the $40k Z-R2.

    5. How much cheese can you stick on an otherwise nice truck? Who are the suckers falling for this? The only thing on this truck with any off-road credibility are the tires. Everything else is garbage that anyone with a $500 gift card to AutoZone can get. Off-road tuned suspension just means they threw on a set of cheap rancho shocks. The “sport bar” serves no purpose other than to block visibility, prevent you from using a bed cover, and let everyone on the road know that you are a tool. Since when are floor-mats part of an off-road package? The only thing this GMC rep is right about is that chances are whoever buys this truck will be the only one on their block with one. You figure out why. Hint- it’s not a compliment.
      Maybe GM should have used their resources to relocate that ridiculous DEF tank which hangs down below the frame just begging to be ripped off by a rock or other obstacle. Now that would be something worthy of an off-road package.

      1. You stole my thunder on this one. Man all that black crap looks just awful and when is GM going to do something with that DEF tank that looks like it was designed as a school project by 5th graders?

    6. Notice gm didn’t have there 6.0 gas engine in this truck? What does that tell you about that engine? They are not even promoting it. That is sad if you are gm fan and don’t want a DSL.

      70,000!? Mercy not sure if i would take it to the rocks.

      Hey rocks! come get me I’m hanging here to get snagged off my frame so I can spill my def all over the ground!

          1. I’m glad you guys like your 6.0 , but it is old with no improvements since….. I don’t know when. 5.7 ram is better than 6.0 in the 3/4 ton market.

            Plus side about 6.0 you don’t have to worry about that def being ripped off the frame.

      1. The 6.0L is a bullet proof engine and is a work horse. It is a low volume engine as most HD owners want a diesel. So why retool an engine or replace an engine if the engine you are replacing is already the most reliable gas HD engine made?

        1. So why retool ? Because the competition is not going to stop improving. That is why you retool!

          Look guys don’t you all want better gas engine than what gm is providing in there heavy duty p/u’s? Yea sure they have reliable engine ,but so does the others that is lot better in performance. If I was a gm fan i would be upset to have an gas engine that was not improved in long time. GM pride themselves to be 1st in class in performance, but right now they are LAST in class in performance with this 6.0 in the heavy duty p/u’s.

          I look at all the gas engines in the heavy duty p/u’s and they are not that impressive. DSL at this has gotten so expensive that a common man can not buy them, because of that they are not real impressive anymore. So there is huge gap between the gas and DSL and gas is now lagging behind with out much improvements in there performance.

          Dpach and others I want better product than what we got today. I’m sure you all wanting the same thing to.

          1. This is why ford needs to go small displacement V8 ecoboost. 450 hp and 650 ft-lbs is plenty but they could certainly go higher without too much trouble. No one could whine about it being a V6 and it would provide plenty of towing power.

        2. I believe you are starting to see a swing back to HD gas engines due to the EXTREME cost of these diesel packages and the fact that it appears that in most of the country diesel costs more than gas so that offsets any fuel economy advantage. Unless you are towing heavy all the time you are probably better off with the gas engine. Especially if you have employees driving your trucks around such as construction and landscapers do.

    7. “automatically locking rear differential”

      Is this a conventional clutch-based LSD, or is it a genuine “locker”? If it is really an automatically engaging-while-moving true locker, that would be quite an accomplishment.


      1. It really is a locker- nothing new though- AFAIK still basically like the old Gov-loc Gm has used for decades. Differental with spider gears and a clutch stack, but it also has some bits that lock left and right together if there is excessive spin.

      2. The automatic lockers serve three.

        1) They lock by themselves
        2) They can be used as a bomb to fight ISIS
        3) They save fuel because GM knows they will explode if abused which is why GM makes their trucks so gutless off the starting line, thus saving fuel and thus keeping their G80 from exploding.


      3. It is the old G80 Gov-lok made by Eaton…same unit that has been in GM trucks for years. It uses a flyweight and centrifugal force to cause the axles to lock together. It is fully automatic but requires some wheel spin before it engages. There are no indicators that come on if it is locked or not, and no driver intervention.

        It works pretty well in most situations, but it is not useful for rock crawling. It is not super strong, but strong enough…helpful when snowplowing.

        1. The G80 Eaton-Fuller locking rear diff requires approx. 100rpm difference between the two rear wheels before it engages automatically. So very little slippage is required (less than 1 second). There is no driver input required. It unlocks once the vehicle is over approx. 25-30 mph or if is no longer sense wheels slippage. Benefits are that both wheels get equal power at the same time to get you moving (as compared to limited slip which sends most power to the wheel it thinks will get the most traction through the clutch pack on that side so really still only one wheel trying to get you moving because the clutch pack on the slipping side won’t be engaged and thus limits the torque/power to the slipping wheel – simple explanation I am sure others on here will complain about). The downfall is that is won’t stay engaged at the same higher speeds a LSD will stay engaged at and it won’t stay engaged around a corner unless the inside wheel can slip on the road surface.

          For 4×4 enthusiasts, using locking rear diffs is preferred because when in 4×4, you are actually getting power to all 4 wheels when spinning. Since LSD send the majority of power to one of the two rear wheels (the one it thinks will get the best traction), when in 4×4 and spinning you actually have a 3×4 since the slipping rear wheel really gets very little or no power because it’s clutch pack won’t be engaged.

          This G80 system has been used for years and it is a very good system. It is heavy duty enough for any reasonable LD and HD truck applications. For those who like to rock crawl, do mud bogs, etc, yeah it can have issues if used heavily but then again it wasn’t designed for that. It was designed to get a vehicle up and moving when on a slippery surface.

          I am sure others will say I oversimplified the explanations and it is much more detailed but for here on this forum, it is adequate.

          1. I have this in my truck. It is fantastic for everyday driving. Especially in winter conditions in Canada. And is quite sufficient for 95% of offroading.

        1. The E-locker is nice, but its a PITA sometimes to have to engage it on the fly if you are not expecting bad conditions. I have always said I would rather have a Tru-trac or something similar instead. The G80 is similar I guess, but I dont remember them lasting on my parents GM cars growing up. The astro van we had def was not working and my dad insists his Trailblazer SS’ is not working, although its hard to tell with the full-time AWD.

    8. I’m not sure why Andre says GM did not have the opportunity to re-design or relocate their DEF tank. They changed the capacity from 5 to 7 gallons, so clearly they redesigned it!

      I think they have no desire to relocate it. The tank is located extremely close to the DEF dosing module…which means the length of heated hose is very short…which saves money. Probably very few people have reported problems with cracking the DEF tank…so despite being unsightly…is functional.

      1. I agree on this one. Our service department has yet to see a truck with a cracked or punctured tank and we are in the middle of Canadian oil production. I’m not saying some haven’t had it happen, but it is not common.

        As I have mentioned before, GM told dealers that they felt it was more likely to be hit or punctured if it was mounted between the frame rails than right behind the wheel because drivers will straddle an object usually (rock or tree trunk, etc) instead of driving over an object with their tire. So anything in line with the tires would likely be safer. Makes some sense but not sure I buy it completely.

        I do know of one Ford which had its tank hit by a 6 inch tree trunk when the owner drover over the trunk with his tire causing the far end to jump up and hit the tank. Again, very uncommon but shows no location is guaranteed to be completely safe.

        The current location is very close to the dosing module which good for a couple reason:
        1. Less lines which means less $ spent.
        2. Shorter lines mean less lines to freeze in winter, less heating elements required to thaw lines, etc.

        1. Dpach, when the engine is shut off the DEF pump clears the lines so they cannot freeze. The lines are not heated just the tank.

      2. It could possibly mean they didn’t have a chance to move the DEF tank since it was originally designed for that spot back when the current HD frame debuted in 2011. I wouldn’t be surprised if this new DEF tank uses the same mounting hole location as the old one. So when the next frame revision comes around, then hopefully they’ll be able to shuffle some things around under the frame to then allow them to move the DEF tank location.

            1. Great engine with limited ratings. Now that seems to be contradiction here. How can it be a great engine if it has limited ratings?

            2. Every engine has its limitations including diesels. I suppose you want a gas engine that outpulls a diesel and still gets 20 mpg.

              Great engines are engines that match or beat the competition and have better reliability. The 6.0L beats the Ram and Ford equivalents plus has the reliability.

    9. Have to laugh at how people get mad over what a truck is called versus what they expect it to do.

      Example is this All-Terrain X. I guess some people take All-Terrain X to mean “Anywhere on the planet” type terrain otherwise it isn’t all-terrain. I guess if GMC called it the Some-Terrain-Depending-On-Regional-Topography-And-Customer-Intent X package people would understand its not a mud bogging rock climbing truck. The only thing on this truck that limits where a can go is the front air dam which is removable. If you consistently go places where it is a hang up, remove it permanently. If you need 18″ of ground clearance, put a lift on it. If you drive it in mud bogs, put a snorkel on it. And so on.

      If you’re after a serious off-road vehicle, buy a ZR2 or Raptor.

      This package gives customers who want a more aggressive tire and a limited production look the option of getting it from the factory and covered under the 3 yr warranty whereas the same accessories bought through a dealer accessory department only comes with one year warranty and it must be installed by the dealer. This dealer install usually means the same accessories are more expensive done through a dealer due to labor rates and shipping of the parts to dealers than if they had installed them at the factory like this truck has.

      1. I don’t think anyone gets mad or even cares what they call it. I think people don’t like to have marketing reps insult their intelligence by spewing nonsense like anything other than the tires make this truck any more capable than your standard 4wd Sierra. Remember that there is a significant up charge for this package. As such, it’s reasonable for people to question what they are actually getting as part of it. In this case, pretty much nothing other than cosmetic items.
        The warranty argument also falls flat on its face. Which of these so called off-road accessories would you say benefit from the factory warranty?
        Rubber floor mats? Body colored door-handles? The unsightly contraption bolted to the bed? The tires are covered by the same manufacturer warranty as an aftermarket set of the same tires.
        And lastly- “limited production” my ass. As Jerry Seinfeld once joked, it’s only limited to the number they can actually sell. You think if there was a market for these, GMC wouldn’t crank out as many as they could?
        I think GMC has a great truck. I’m just poking fun at these silly marketing ploys.

        1. And its not just that GM insults the buyers intelligence, it’s embarrassing to see. The guy with the bed-sports bar looks like a tool and the name of the truck is a tool. I feel embarrassed even if it parked beside me at a light. It is like being on stage with an ass….you just want to leave. Shocks are not even good enough for bad road conditions let alone off road terrain.

          And as per the manual improper air flow goes to the motor with the air dam removed. Then you have a shitty suspension with step bars that further hinder clearance and those stupid bed bars that just add weight and F your box space and don’t allow for a bed cover. Just add a tire package and that would be far more commendable or give us a different front bumper design with Bilstein or Fox shocks.

          1. Amen, my brother.
            I could attach a skid plate to my nut sack but it still wouldn’t make it smart to dangle it 6 inches from the road like that DEF tank.

        2. I’d also like to echo that it’s not anger, it’s a sense of vicarious embarrassment. Their gimmicky marketing efforts are just cringe-worthy.

          They’re pretending that this is some sort of limited edition off-road beast when all they did to improve its off-road capability was throw on some tires anyone could buy almost anywhere (more than likely for a lot less than the markup GMC is putting on them) and attach a set of sorry Rancho shocks in place of the normal stock ones.

          The rest of it is just gross JC Whitney catalog stuff. That horrid bed bar. Those dinky, silly looking lights. That laughable skull-shirt inspired name.

          It still has that catfish-chin air dam that almost touches the ground. It still doesn’t have lockers.

          Someone should tell them that Ed Hardy and calling things “X-Treme” both went out of style 10 years ago.

          1. @RNUOVR,
            “I’d also like to echo that it’s not anger, it’s a sense of vicarious embarrassment. Their gimmicky marketing efforts are just cringe-worthy.”

            Nicely put….and subject to criticism as a result, leading to poor and hurtful advertising for the entire line-up of vehicles they sell. Take note of the positive feedback from the ZR2 when you do something right.

            1. Exactly. Who is trash-talking the ZR2? Nobody. Sure, a lot of folks question the concept of paying *that much* for a midsize truck, but it is actually a serious off-roader with real, substantive mechanical improvements over the normal 4×4 version of the truck. Not a “stickers & JCWhitney bolt-ons” package that marketing people are going to have to try to sell as a way to get an obscenely overpriced warranty on running boards and a light bar.

        3. As for the warranty issues I’m not so much talking about this one package as manu’s get lots of slack for adding accessories and charging a premium for them all time. People have to realize it is cheaper to install them from the factory than buy OEM accessories and pay a dealer to install. Plus things like OEM running boards, tonneau covers, box rails, bull bars, light bars, etc do have issues from time to time that warranty looks after. Powder coating can chip, chrome can chip/crack/peel, seals can leak water, connectors break in cold weather, etc which is covered by GM’s 3 yr warranty when factory installed.

          As a consumer, perhaps you’ve never had an issue but as a 20 yr person in the automotive business, I’ve seen many accessories with warranty claims.

          These are clearly not your cup of tea. But do you honestly think Ford (tends to make them a model, not a package) Ram and GM would take their time to put these editions together if there wasn’t a strong market for them? Clearly they are appealing to a lot of people. Your opinion is just that; one person’s opinion(and you are entitled to that) who these don’t appeal to.

          As for limited production, you are clearly taking my point as meaning a “1 of 100” type limited production. Take a pill duke. What I meant is that GM is not going to flood lots with this even if every dealer ordered nothing but these. We tried to order a ton of Midnight Edition Silverados because we had so many people wanting them but GM put a limit on how many they would build. Yes it wasn’t 100 or 1000 units, but it also wasn’t 100,000 either.

          1. The Midnight Edition Silverados were tastefully done. There was a market for them. What they did was “murder-out” a truck from the factory. They didn’t try to claim it was a performance enhancement and they didn’t bolt on a bunch of cheap, tacky junk or paint on random stripes. They were understated and good looking.

            I think GM took the success of Midnight Edition to indicate something it really wasn’t saying: which is “people want a whole bunch of different un-special special editions that really have nothing special about them”, when in reality the Midnight Eiditon actually sold well because it tapped directly into the desire of people to murder out their trucks and make them look clean. I don’t think there’s a lot of desire out there for camo stickers, racing stripes, blackout editions with random red stripes on the wheels, and sport bars in the bed. That’s all pretty much the opposite of what made the Midnights desirable.

          2. Dpach, I appreciate your industry experience and your comments. My “limited edition” joke was not directed at you but rather at that GM marketing guy in the video. I’m not a fan boy of any particular brand and I agree that all three are guilty of these marketing antics. My point is that these add-ons, tacky as they are, should be sold and marketed as appearance packages. It’s very disingenuous when they are marketed as anything more than that.

            1. I hear what you are saying and agree with you to a point. But we can’t forget that a marketing guy is paid to market some hype and gain attention to a product. These guys are doing their jobs. We don’t always agree with it but since all three brands are still doing this (and Ram is really following with their new editions), it must be working. Have there been some flops; oh yes. Just look at the hideous Duck Dynasty GM’s with the camo decaling and interior trim. It was horrendous. We didn’t order many but those we did sold. The most common customer for us were outfitter companies.

              Ford used to market them as appearance packages but then turned them into actual models. Remember the original FX4 (shocks, tires, skid plate, decals) which is now a model. How about the Harley Davidson which was rims/tires, decaling, interior trim upgrades and suspension tweaks. It became its own model.

              We have to remember that almost every “Special model” is just a regular model with accessories added; some suspension/tires, some decaling and trim. Ram’s Rebel is just a Ram with accessories and upgrades that anyone could buy aftermarket wise and make their own or better. The only two trucks that really can’t be made (economically) are the Raptor and ZR2.

    10. Thanks for the explanations Dpach. I always wondered why trucks don`t all come with some form of diff lockers as they are especialy useless without cargo on a slipery surface. So most regular 2 wheel drive trucks are truly 1 wheel drive. OK for dry pavement I guess.

    11. I like GM products, but they have to get a real e-locker in the rear, and ditch the cheesy 1990’s roll bar. I think Tango and Cash designed that truck.

    12. GM(government motors) does not sell many 3/4 ton trucks so i wouldnt expect to see very many of these hoopties on the road. Ford by far has the best heavy duty 4×4s on the market. There is nothing tougher then the super dana 60 solid axle up front in the super duty. The Ford rides way better then gm IFS.

      1. Where do you get your information that GM doesn’t sell many 3/4 ton trucks? Where is your info to back it up?

    13. Really starting to think GM doesn’t pay the marketing department. Just a lame idea here. Come up with a worthwhile special edition already or just stop.

    14. I like most of this truck a lot. The all black theme does work. I still cannot like the headlights. At least to me they just look really odd. The silverado i think looks much better. I would still drive this truck though.

    15. I think if you are really serious about off roading both the Ford Raptor and the Ram Power Wagon are far superior. This is basically a HD 2500 with some black trim and other garbage thrown on it.

    16. The 6.0 just needs forced induction even a mild 4 to 6 psi with good intercooling would make an easy 450hp/500lbs. With more torque down low where u want it then they could use same allison and rear as duramax.

      1. The question is are the main bearings, holders, rods, rockers, crank, etc strong enough for that hp/torque or would they also need an upgrade? One upgrade can easily lead to another, to another, etc and before you know it, you have a new engine that cost millions to do (R&D, testing, etc) for a really small market/demand. I think the demand would increase for that type of gas engine especially if they could mate it with the Allison but would it be enough increase to return profits on the investment?

        1. I’ve heard of folks pushing 1000 whp on stock bottom ended iron block GM motors. There was a guy i remember seeing videos of(back when I had my 2006 GTO and paid attention to GM stuff) that had a RCSB Silverado with a Procharged 5.3L at over 900 whp. I think they are pretty stout motors from the factory.

          1. They are pretty stout but as a manufacturer would you want to warranty that hp for 3yrs (5 yrs in Canada)? The engines can probably handle it but would it be a 10 yr – 200,000 mile motor?

            The reason GM doesn’t put the 6.2L in the HD’s is because the basic block design isn’t strong enough for everyday HD requirements. That is they have kept the 6.0L around so long (heavy main bearings, cranks, etc).

        2. If there’s a motor that could stand up to it reliably, it’s the 6.0. That thing is a battle axe. The reason GM hasn’t replaced it yet is that they have been very successful in gearing around its shortcomings and most HD gasser sales are fleet. Fleet managers don’t care about speed just reliability. Which brings this discussion full circle, because that’s why they won’t add forced induction to the 6.0 – it satisfies their customers as-is, thanks to smart gearing and bulletproof design.

            1. Round rubber tires are old and outdated. They should be replaced. Geared transmissions are old and outdated. They should be replaced.

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