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Longer and roomier inside, the 2021 Chevrolet Tahoe leverages GM’s new full-size-pickup underpinnings – but with some SUV-unique twists. (Chevrolet)

All-new 2021 Chevrolet Tahoe, Suburban get IRS, inline-6 diesel

For its 2021 full-size luxo-SUVs, Chevy goes for more size and more sophistication.

Although the full-size SUVs from General Motors’ Chevrolet brand have a long history and reputation built on their tough pickup-truck foundation, it’s apparent Chevy’s pinpointed enhanced comfort, space and luxury as the primary engineering points for the all-new 2021 versions of the Tahoe and its longer-but-mechanically identical counterpart, the Suburban. The new models go on sale in the middle of 2020.

A large portion of the 2021 Tahoe and Suburban’s new design brief comes in the form of a first-ever independent rear suspension (IRS) for the two nameplates (although chief competitor Ford Expedition incorporated that feature in 2003). This brings the twin advantages of reduced floor height to significantly increase cargo volume and legroom in the third-row seats, as well as ride-and-handling enhancements typical of IRS compared with a solid rear axle.

New chassis = more space all around
The new Tahoe/Suburban’s ladder-frame structure is largely based on that of the current-generation half-ton and three-quarter ton Chevy Silverado/GMC Sierra pickups first introduced for the 2019 model year, including the short/long-arm front suspension, plus added frame spans for additional length. The IRS adds a new dimension, and Chief Engineer Tim Asoklis said the combination delivers a “big increase” in cargo space behind the SUVs’ third-row seats, a design and layout bugaboo that’s afflicted modern-day versions of these models. For the new Tahoe, that equates to 66% more cargo volume behind the third row and a whopping 40% more rear-seat legroom.

For the larger Suburban, second- and third-row passengers now enjoy an extra 2.3 in (58 mm) and 2.2 in (56 mm) of added legroom and total cargo volume increases by 19%, despite an overall-length increase of just 1.3 in (less than 1%). Total length goes from the 2020 Suburban’s 224.4 in (5700 mm) to 225.7 in (5730 mm) on the 2021 version. For the 2021 Tahoe, wheelbase increases from 116 in (2946 mm) to 120.9 in (3071 mm) and overall length for the new model gains 6.7 in (170 mm) to a total of 210.7 in (5352 mm).

This IRS is tax-free
Asoklis said the IRS for the 2021 Chevrolet Tahoe and Suburban couples with available Magnetic Ride Control and a new Air Ride Adaptive Suspension (air suspension is said to be a segment-first) for the most-advanced suspension in the full-size SUV segment. Base models will use a conventional steel spring/damper setup, while mid-trim models will offer the magnetic-ride upgrade. Top-trim High Country models will offer the air suspension in addition to the magnetorheological dampers.

The air-suspension setup enables raising or lowering the ride height over a 4-in (102-mm) range. The chassis also is lowered at higher speed to reduce drag and the system also can be used to ease trailer attachment and to maintain ride height with heavy cargo loads. The IRS setup – three lateral links and a single longitudinal link – lowers the cargo floor by a significant 5.5 in (140 mm), Asoklis said, while also playing a major role in providing the newfound third-row legroom. He said the new rear-suspension design also means the models finally will boast a “virtually flat” cargo floor.

Engineers were not specific about how much weight the new IRS may have added and Chevrolet did not yet detail curb weight for the new models. The 2020 Tahoe weighs as much as 5772 lb (2618 kg) in its heaviest specification, the 2020 Suburban weighs as much as 6021 lb (2731 kg).

New power option: diesel
As is current practice, the 2021 Tahoe and Suburban offer two gasoline V8s, a 5.3L and 6.2L, making the same power as before: 355 hp and 383 lb-ft (519 Nm) for the 5.3L and 420 hp and 460 lb-ft (621 Nm) for the 6.2L. These engines deliver the same output for the brands’ pickup trucks. But also mirroring the pickups’ powertrain lineup is a new wrinkle for full-size SUVs in the availability of GM’s new 3.0L inline 6-cylinder turbodiesel, first launched in the pickup line.

In the new full-size SUVs, the diesel develops 277 hp at 3750 rpm and 460 lb-ft (623 Nm) at 1500 rpm. A powertrain NVH engineer said there are some specific sound-abatement measures for the diesel, the most notable being a thicker firewall mat. The diesel also uses unique engine mounts, though primarily to accommodate the weight of the engine. All three engine choices are backed by the widely-used Hydra-Matic 10L80 10-speed automatic transmission and perhaps surprisingly, the same 3.23:1 final-drive ratio is used regardless of engine choice.

New electricals, too
Another significant technology for the new Tahoe and Suburban is the adoption of GM’s new digital electric architecture, an “all-new technology that enables a lot of things,” said Gary Bandurski, executive director of Global Electronic Components and Subsystems. Recently fitted to the Cadillac CT5 and the upcoming 2020 Corvette Stingray, the 2021 Tahoe and Suburban mark the first truck application of the digital electrical platform, which Bandurski said has approximately five times the processing capacity of GM’s current systems – enough to move 4.5 terabytes per hour, the equivalent data of 980 digitized movies.

According to Bandurski, the system improves speed and functionality and also enables new vistas for over-the-air (OTA) software upgrades and other potentially critical updates, greatly enhancing the system’s cybersecurity capability. Although customers will not necessarily notice many of the system’s advantages, he said some apparent dynamic aspects will include faster brake response, and smoother and more accurate accelerations and decelerations while using adaptive cruise control. Further, adoption of the system means all onboard cameras now are digital (currently, a mix of analog and digital has been employed) and all are at least one megapixel in resolution.

More trim levels
When they go on sale in the middle of 2020, the 2021 Tahoe and Suburban will be offered in six trim levels, double the current lineup. The base LS and LT models are the foundation trims, joined by a street-oriented RST, the well-known Z71 off-roader, Premier trim and the range-topping High Country. All of the 2021 full-size SUVs will be sourced from GM’s Arlington, Texas assembly plant.

The Arlington plant underwent a $1.4-billion upgrade to accommodate the new models that included a 1.6-million sq-ft expansion to accommodate a new body shop with 1,450 new robots, nearly double the current count of 750. Teri Quigley, executive director, Launch Excellence, said highlights include a new front-end integral body-assembly process, two hulking robots that marry the entire body structure with the chassis in a single motion, and more than double the welds of today’s models.

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