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2015 GM Fullsize SUVs: On- and Off-Road Test

Posted in Vehicle Reviews on April 4, 2014 Comment (0)
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2015 GM Fullsize SUVs: On- and Off-Road Test
Photographers: Courtesy of General Motors

How would you like to be tasked with the redesign of the Chevy Tahoe, Suburban, GMC Yukon, and GMC Yukon XL? These are powerhouse nameplates. Succeed and you’re a hero. Fail and you’re something that rhymes with hero but isn’t. No pressure.

In the January 2014 issue of Four Wheeler, we gave you some info on the all-new 2015 GM fullsize SUVs. At the time, we were granted access to the vehicles in advance of their official unveiling, but weren’t allowed to drive or photograph them. Recently we had the opportunity to do both. During a drive from Napa, California, to Olympic Valley, California, we drove all of the aforementioned vehicles on a variety of road surfaces from twisty two-lane to flat four-lane. There was no off-road travel slated for this drive, so we defected from the paved road a couple of times to get a feel for how the SUVs handled the dirt. Sorry GM, it’s what we do.

On-road, the first thing we noticed is that the interior of these new SUVs are amazingly quiet at speed. The noise-reducing technology that GM integrated into the design of these machines has paid off in a big way. Items like a laminated windshield and door glass, a flatter windshield (1-degree) and a new outside rear view mirror design contribute to far less noise permeating the cabin. Even at highway speeds, we could tone down our “inside voice” and carry on a conversation in almost a whisper. We think cabin quietness is on par with even the most lofty-priced luxury SUVs and is amazing considering the cavernous interior space. And speaking of the interior, we were impressed by the new seating, the increased second-row legroom, and the power fold-flat third-row seating. Heck, you can even get heated, power fold-and-tumble second row seating. We tried to nitpick the interior for something to gripe about, but came up short. From technology to storage, the new SUVs have it covered.

The first vehicle we drove was this top-of-the-line Yukon XL Denali. Base price was $68,380, but this particular rig had a sticker price of $77,965. For that price, one would expect a lot, and there were no disappointments. It came equipped with real wood trim, the 6.2L V-8 engine, unique seats with more premium leather, Magnetic Ride Control, Bose Centerpoint surround sound system, heads-up display, and much more. The first vehicle we drove was this top-of-the-line Yukon XL Denali. Base price was $68,380, but this particular rig had a sticker price of $77,965. For that price, one would expect a lot, and there were no disappointments. It came equipped with real wood trim, the 6.2L V-8 engine, unique seats with more premium leather, Magnetic Ride Control, Bose Centerpoint surround sound system, heads-up display, and much more.

Overall drivability on-road is also vastly improved. The 5.3L and 6.2L EcoTec3 V-8 engines are some of the most high-tech available and feature direct injection, active fuel management, and continuously variable valve timing. The 6.2L (found in the Denali-trimmed GMC Yukon and Yukon XL) punches out 420hp and 450 lb-ft of torque and was more than adequate for pulling the heavy Yukon XL Denali up mountain roads or when passing. The 6.2L is rated at 21 mpg highway in the GMC Yukon Denali and 20 mpg highway in the GMC Yukon XL Denali four-wheel-drive models, which we think is respectable. The 5.3L (the only available powerplant in the 2015 Chevy Tahoe and Chevy Suburban and the standard engine in non-Denali GMC Yukon and GMC Yukon XL) produces 355hp and 383 lb-ft of torque and is also no slouch in the power department. The 5.3L engine is rated at 22 mpg highway in Tahoe, Chevrolet Suburban, GMC Yukon, and GMC Yukon XL four-wheel-drive models. These engines worked seamlessly with the Hydra-Matic 6L80 six-speed automatic transmission, which has auto grade braking, tow/haul mode, and improved TAP shift technology.

As we clicked off road miles behind the wheel of these new SUVs we were impressed at how well they handled, not only on the highway, but also on the twisties. This is due to a number of improvements including wider wheels that help with cornering, a wider rear track, retuned suspension and new electric variable-rate power steering that tailors steering assist to vehicle speed. And when it came time to scrub off speed, larger brakes made it a no-drama event with good pedal feel. In the end, we felt that all of the vehicles handled like smaller vehicles, and that’s a good thing in our opinion.

The 6.2L V-8 engine is exclusive to the high-zoot Yukon Denali and Yukon XL Denali. This engine produces 19 percent more horsepower and 20 percent more torque than the 5.3L V-8 found in the other GM fullsize SUVs.     The 6.2L V-8 engine is exclusive to the high-zoot Yukon Denali and Yukon XL Denali. This engine produces 19 percent more horsepower and 20 percent more torque than the 5.3L V-8 found in the other GM fullsize SUVs.

Off-road travel is where it’s at in our world and we had a chance to briefly get into the dirt in the 2015 Chevrolet Suburban (this is also the vehicle we spent the majority of our time with). The Chevrolet Suburban we were piloting was an LTZ-trimmed model equipped with the Magnetic Ride Control suspension as well as G80 locking rear differential. On graded dirt roads the ride was fantastic, the body structure tight, and the steering precise. The street tires gripped surprisingly well, undoubtedly aided by the locking rear diff. But as is typical, we found that many of the things that help to improve fuel mileage hinder off-road travel. Ground clearance on this vehicle was only 7.9 inches and the approach angle was only 15.5 degrees. For comparison, these numbers are lower (that means worse) than the ’14 Dodge Durango that competed in our 2014 Four Wheeler of the Year test and even lower than a ’14 Subaru Outback. It hasn’t always been this way. The ’03 Chevrolet Suburban 4x4 had better ground clearance (8.4 inches) and a 9.5-degree better approach angle (25 degrees). But here’s the thing: The lower stance is one of the keys to improving aerodynamics that help generate the required fuel mileage numbers. Some things have to be sacrificed it seems, and in this case those some things are approach angle and ground clearance. An off-road package could potentially help, but GM is not offering one on the 2015 models. Thus, we had to be acutely aware of trail conditions that could damage the low-hanging front fascia or contact the underbelly of the rig.

10 Tech Highlights

The all-new 2015 GM Fullsize SUVs sport a lot changes. The exterior changes are obvious, but there are a significant number of changes that can’t be seen. Here are 10 tech highlights of the new SUVs.

-Engine cooling performance has been increased

-Electric power steering has been added, thereby reducing drag on the engine and the need for a power steering cooler

-To compensate for the increase in power, the transmission has internal modifications to aid in durability and calibrations have been improved

-Upgrades for T-case durability include seal upgrades and software changes

-Vehicles equipped with the 5.3L V-8 get the 9.5-inch rear axle and 6.2L-equipped vehicles get the 9.75-inch rear axle (both are approximately 1.75 inches wider than the previous generation)

-The front differential is updated with new mounting provisions

-There are thicker-walled and larger diameter front and rear driveshafts

-All of the IFS control arms and knuckles are aluminum (all are cast except for the upper control arms, which are forged)

-The frames are structurally stiffer, have new shear-style body mounts and some frame crossmembers have been redesigned

-All available wheels are wider by ½-inch to improve stiffness

We got a little off-road time in the Suburban and we appreciated the decent 37.5:1 crawl ratio and the G80 rear locker. We were less enthusiastic about the 15.5-degree approach angle. The low hanging front end could create the equivalent of an anchor in situations such as sand or snowdrifts.  We got a little off-road time in the Suburban and we appreciated the decent 37.5:1 crawl ratio and the G80 rear locker. We were less enthusiastic about the 15.5-degree approach angle. The low hanging front end could create the equivalent of an anchor in situations such as sand or snowdrifts.

If We Had Our Way

We’d love to see an off-road package that creates a better approach angle and ground clearance. For these vehicles, an air suspension system that offers the ability to increase the suspension height would be ideal. This would offer the ability to keep the vehicle low for highway use and retain the good fuel mileage, while offering improved approach, departure, and rampover at the push of a button. A more aggressive, slightly larger diameter tire, an easy to clean wheel in a conservative diameter and underbody skidplating would also be on the list. In regards to the Suburban, we’d love to see a ¾-ton model with a Duramax diesel engine option. We noticed that in some press material we received from GM they specified the Suburban we drove was the ½-ton model, so we’d like to think a workhorse ¾-ton is in the works.

Pricing

Official pricing for the 2015 GM fullsize SUVs is as follows. Prices do not include tax, title, destination charge, dealer fees, special offers, or optional equipment like four-wheel drive (four-wheel drive adds approximately $3,000).
-Chevrolet Tahoe $44,600
-Chevrolet Suburban $47,300
-GMC Yukon $46,335
-GMC Yukon XL $49,035
-GMC Yukon Denali $58,320
-GMC Yukon XL Denali $60,985

QUICK SPECS (as tested)

Vehicle/model: ’15 Chevrolet Suburban ½-ton LTZ 4x4
Base price: $64,700
As tested: $71,385
Engine: 5.3L EcoTec3 OHV direct-injected V-8
Rated hp/torque (lb-ft): 355/383
Transmission: Hydra-Matic 6L80 six-spd automatic
Transfer case: MP3023 two-spd
4WD system(s): 4-Hi, 4-Lo, Neutral, 2WD
Low-range ratio: 2.72:1
Frame type: High-strength steel
Suspension, f/r: Independent, Magnetic Ride Control, stabilizer bar/five-link, Magnetic Ride Control, stabilizer bar
Axles, f/r: 8.25-in/9.5-in
Axle ratio: 3.42:1
Max crawl ratio: 37.5:1
Steering: Electric power-assisted rack-and-pinion
Brakes, f/r: 13.0-in/13.6-in
Wheels (in): 20x9
Tires: P275/55R20
Wheelbase (in): 130
Length (in): 224.4
Height (in): 74.4
Width (in): 80.5
Base curb weight (lb): 5,896
Approach/departure angles (deg):15.5/21.1
Minimum ground clearance (in):7.9
Payload (lb): 1,643
Max towing capacity (lb): 8,000
Fuel capacity (gal): 31
Fuel economy (mpg): 15 city, 22 hwy

Bottom Line

There’s no question that the new 2015 GM fullsize SUVs are the tightest, most luxurious, powerful, fuel efficient, smoothest riding vehicles to wear these badges and the team tasked with the redesign should be proud of them.

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