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  • 2021 Chevrolet Suburban High Country Diesel First Drive

2021 Chevrolet Suburban High Country Diesel First Drive

Our take on the 3.0L Duramax and ten-speed automatic’s debut in Chevy’s all-new fullsize SUV.

Dec 11, 2020
A recent memory-lane-style television commercial for Chevrolet's all-new 2021 Tahoe and Suburban opens with an announcer saying: "Since pioneering the SUV in 1935, Chevy Suburbans have carried many things," and then it goes on to close with "family being most important" as the sentimental punchline. Yes, when it comes to precious cargo, dad, mom, kids, and pets are always number one.
However, to move that important payload and anything else, a capable drivetrain is necessary. For years, 65 to be exact, gas-powered V-8 or diesel engines of varying displacement have handled that task. The gassers' run is steady—with 5.3L and 6.2L powerplants being the platform's current petrol burners—but diesel has only been part of Suburban's makeup for 17 years (naturally aspirated 6.2L Detroit Diesel from 1892-1991, 6.5L turbodiesel from 1992-1999). Until now.
Twenty-one years after the 6.5L's retirement, diesel is back in Suburban's engine group as a 3.0L I-6 option for LS, LT, RST, Premier ($995), and High Country ($1,500) models; the same powerplant that debuted in Chevy's 2020 Silverado 1500. The 3.0L retains its 277 hp and 460 lb-ft of torque in the big SUV and, similar to all of Chevy's fullsize trucks, is coupled to a ten-speed automatic transmission that manages forward and rearward motion.
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Like most enthusiasts who anxiously anticipated the two renewed rigs, we were surprised to learn the 3.0L Duramax is also the 'Burban's oil-burner option, and not the 6.6L V-8 turbodiesel found in heavy-duty Bow Tie pickups. At first thought, the 3.0L makes sense for the smaller 2021 Tahoe, which, depending on trim level and powertrain, is approximately 200-plus pounds lighter than the Suburban.
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But conventional assessment of power-to-weight has us wondering how and where the I-6 powerplant wins in the bigger SUV, which has considerably less horsepower (277 hp to the 5.3L's 355 hp and the 6.2L's 420 hp) but as much torque (460 lb-ft to the 6.2L's 460 lb-ft) or more (460 lb-ft to the 5.3L's 383 lb-ft) than its two gas engines have.
To help us answer those questions and learn more about the new-generation Suburban, Chevrolet gave us a decked-out, Duramax-powered High Country to drive and experience for a quick 24 hours; a first-drive opportunity that was granted mere weeks before the all-new SUV hit dealers' showrooms.
The following photos, data, and videos reflect Diesel Power editor KJ Jones' experience with the new Suburban High Country. Although the test unit is four-wheel drive, KJ did not have an opportunity to drive it off-road, and towing could not be evaluated due to severe wind conditions in Southern California's San Fernando Valley and Ventura County areas.

New Size and Style

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On the outside, the redesigned Suburban High Country looks sharp, with its chrome grille, updated headlights, and taillights, and especially in the Graywood Metallic color that was applied to our rig's body panels. At 134.1 inches, its wheelbase is 4.1 inches longer than the previous generation's, and the SUV's overall length has grown to 225.7 inches (up 1.3 inches). The wheelbase update is a boon for rear passengers.
Yes, size bumps inside are considerably greater. Passengers (High Country seats eight) now have 181.9 cubic feet of space (a 5.8-cubic-foot increase) to be comfortable throughout the cabin. In the second and third rows, Suburban has 2.3 inches of additional legroom (42.0 total inches) in front of the power-release second-row bucket seats and 2.2 inches of additional leg space (36.7 inches all in) for passengers in the power 60/40 split-folding seat in the back.
With the rear seat up, there is 41.1 cubic feet of space for items other than people, and when the back area is configured as a big pallet (second- and third-row seats down), the total cargo space is 144.7 cubic feet.
As a High Country model, our test vehicle has too many luxurious interior enhancements to list here. Seriously. And given our short amount of time with the new rig, we didn't perform a deep study of every bell and whistle. For those details and to tailor a new 'Burban to your exact specifications, go to chevrolet.com/suburban.
The High Country marque includes all the technology—especially in the infotainment area (i.e., Bose surround sound audio, 4G Wi-Fi, Apple CarPlay and Android Auto, SiriusXM radio, a 10-inch touchscreen, and gigantic 12.6-inch screens for second-row passengers)—driver safety/awareness nannies, and creature comforts (Jet Black perforated-leather upholstery with brown fabric in ours, multi-position power seats, panoramic sunroof, all types of temperature controls, including steering wheel, etc. ). Chevy can load into a pickup or SUV. None of it was spared on the rig we received.

3.0L Duramax and Ten-Speed Automatic

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With experience in Chevy's 3.0L Duramax-powered 2020 Silverado 1500 to use as a benchmark, KJ took the 2021 Suburban High Country on a 150-mile tour that included an equal amount of driving on local streets and major Southern California freeways.
In the heavier Suburban (curb weight is in the area of 6,000 pounds), the 277 hp, 460 lb-ft, and ten-speed automatic gearbox are just as smooth and efficient as they are in the pickup. But there is a significant difference in the way the powertrain accelerates the greater mass. Scientific 0-to-60 mph recordings were not taken, but from a seat-of-the-pants perspective, the diesel doesn't struggle to get the big SUV moving.
The drivetrain's response to sudden throttle input is not as hair-trigger as it is in the Silverado 1500. However, similar to the pickup's ten-speed transmission's programming, all shifts are on point and keep the oil burner in the right rpm range at all times.

I, R, and S

No, we're not talking about the U.S. government agency that keeps tabs on our finances. In short form, the magic letters identify an independent rear suspension system, which supports the fullsize SUV for the first time.
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Working in conjunction with Magnetic Ride Control and a very innovative Adaptive Air Ride conglomerate of four bags that manually and/or automatically adjust ride height by up to 4 inches, the 2021 Chevy Suburban High Country is a smooth-riding, uber-comfortable rig that handles very well, given its stature. Although there is a Sport driving mode (adjust the transmission's shift mapping), the introduction of IRS does not make the big SUV handle like a slot car, but it helps improve a driver's overall confidence with maneuvering the long-wheelbase vehicle, especially when driving on uneven road surfaces or changing lanes at freeway speed.
IRS also contributes to the new 'Burban's increased cabin space (passenger-area legroom) and ease of loading the cargo area.
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Fuel Economy

Here's where the burning question, "Why a 3.0L turbodiesel instead of GM's 6.6L Duramax?" gets answered. After driving the Suburban, we believe with its 6.2L-matching 460 lb-ft of torque, the I-6 Duramax has performance capability (with the exception of the aforementioned rapid acceleration) that's on par with Suburban High Country's standard gasser.
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The big difference in the equation is fuel efficiency, and that's where going with the small turbodiesel is justified over its 6.6L sibling. The EPA scores our four-wheel-drive test rig's fuel-mileage statistics at 20/26/22 mpg city/highway/combined. In our test, which unfortunately does not include towing due to high winds, our calculated fuel economy is very close to the government numbers: 20 mpg (city) and 24 mpg (highway).
In a press release announcing EPA fuel stats, Chevy Trucks marketing director Bob Krapes said, "The 3.0L Duramax turbodiesel brings a refined engine experience to the already impressive redesign of the all-new 2021 Suburban
"Combining the segment's best fuel efficiency with increased space inside of the vehicle compared to the previous generation equals an all-new Suburban that's ready for the next long road trip or family adventure."
And there you have it. The "Suburban Way Dad, mom, kids, and pets. Family. Always number one, since 1935.

Vitals

2021 Chevrolet Suburban High Country
Base price: $75,300
Price as tested: $82,495
Engine: 3.0L I-6
Transmission: Ten-speed automatic
Horsepower: 277 @ 3,750 rpm
Torque: 460 lb-ft @ 1,500 rpm
Towing capacity: NA
EPA fuel economy rating: 20 city/26 hwy/22 comb
Actual calculated economy, 150-mile trip: 20.10 mpg
Sources
Chevrolet
https://www.chevrolet.com

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