Chevy & GMC & the Continuing Relevance of Full-Size SUVs

Gary S. Vasilash

While SUVs seemed to have become somewhat marginalized by the Great Recession, the designers and engineers at GM have continued working on improving their products, products that have the lion’s share of the still-important segment.

When you’re engineering an all-new full-size SUV and you pretty much own the market, you want to make sure that the new one is solid and appealing. This is the situation that Jeff Luke, executive chief engineer, Full and Mid-Size Trucks, General Motors, and his team faced when developing the all new Chevrolet Suburban and Tahoe, and GMC Yukon and Yukon XL. So speaking to the strength of the SUVs, he points to the extensive use of high- and ultra-high-strength steels that are used to construct the vehicles:
•    19% <140 MPa
•    29% 180-300 MPa
•    20% 300-400 MPa
•    10% 400-500 MPa
•    17% 500-1,000 MPa
•    5% 1,000+ MPa

Does this mean that the SUVs are all-steel, something that is now thought to be not so au courant? No, Luke points out that the hood and tailgate are aluminum, as are suspension components including the forged upper and cast lower control arms and steering knuckles. He says that the liftgate is a particularly interesting component. It is actually two pieces that are robotically brazed with the seam running horizon-tally across the back, appearing to be more of a design element than a joint. “We use aluminum where we need to,” Luke says.

And speaking to the dominance of the large SUV segment, which GM calculates to have been 263,948 units in 2013, it went like this in 2013:
•    Tahoe: 83,502 units, 31.6% share
•    Suburban: 51,260 units, 19.4% share
•    Yukon XL: 31,258 units, 11.8% share
•    Yukon: 28,302 units, 10.7%

Which gives GM 194,322 units and a 73.6% share.

Some people wonder, of course, about the relevance of a full-size SUV in a market that seems to be going toward things that are smaller and don’t have V8s—fuel-efficient or not—under their hoods. But then in addition to the aforementioned size of the market, it is also worth taking into account that the customers for the vehicles tend to be on the affluent side, with, for example, the customers of the Yukon XL Denali having a median income of $188,000. Any vehicle manufacturer wants to 
keep people like that in the family.

Chevy and GMC recently came out with new full-size pickups, the Silverado and the Sierra, respectively. Body-on-frame vehicles. So it stands to reason that the full-size SUVs would simply follow, with a modification primarily being an additional row of seats and more sheet metal. Luke: “There is no sheet metal sharing from the pickups.” And the insides are different. And the rear suspension setup is different (with the SUVs having a solid axle and five-link coil spring suspension). Luke does acknowledge that from a frame-point-of-view, there are architectural similarities, but this is not a one-for-one transcription.

One area where there is sharing between the full-size pickups and SUVs is under the hood. The standard engine for the models, with the exception of the Denali trims for the Yukons, is the 5.3-liter EcoTec3 engine. The aluminum engine (block and heads) produces 355 hp @ 5,600 rpm and 383 lb-ft of torque @ 4,100 rpm. Thanks to features including direct injection, cylinder deactivation, continuously variable valve timing, and an advanced combustion system, the engine returns an estimated 16 city/23 highway miles per gallon in a two-wheel-drive vehicle, 16/22 mpg in a four-wheel-drive SUV.

The Yukon Denali and Yukon Denali XL come with a 6.2-liter EcoTec3 engine. This engine produces 420 hp @ 5,600 rpm and 460 lb-ft of torque @ 4,100 rpm. It is estimated to provide 15/21 mpg for two-wheel-drive and 14/21 mpg for four-wheel-drive.

Both of the engines are mated to a HydraMatic 6L80 six-speed automatic transmission.

A word about the four different SUVs. From a dimensional point of view, there are really two sets of two, with the Tahoe and the Yukon having the same wheelbase and the Suburban and the Yukon XL sharing the same. But while it would take a superhero eye or a spec sheet to discern the differences, the Tahoe is 204 in. long and the Yukon 20.9 in. long; the Suburban is 224.4 in. long and the Yukon XL 224.3 in., with differences in the front fascias accounting for the 0.1-in. difference.

Nowadays, it is de rigueur for vehicles of all sizes to be fitted with various sensors, most of which are on the exterior of the vehicle. The previous-gen full-size SUVs have a rear vision camera, rear park assist, and side blind-zone alert. The new models are available with many more sensors: radar, ultrasonic, and cameras. They offer forward collision alert, adaptive cruise control, rear cross-traffic alert, and more.

Luke points out full-size SUVs are targets of the criminal element. (Perhaps there is an awareness of the high-income demographic for the vehicles.) So they’ve deployed sensors on the inside of the vehicles as part of an available security system. There are sensors in the overhead console that detect interior motion. There are glass breakage sensors. There is a vertical movement sensor (e.g., should the system be armed and some miscreants jack up the car to steal the 18-, 20- or 22-in. wheels; the alarm is activated). Because sensors can be defeated by having their power source eliminated (as in the battery being disconnected), this system uses a separate battery to power the sensors and the alarms. And on a more mechanical front, they’ve installed door shields in the driver’s door to prevent the use of a “slim jim” device to open it.

Although these vehicles are sizeable, Luke says that one of the issues they determined that people had with them was getting into and out of the rear doors, especially in instances when they are accessing the third row. So they’ve reduced the front doors in size and increased the size of the rear doors; they moved the B-pillar forward and the C-pillar rearward. Consequently, there is improved ingress and egress.

Another part of the SUV functionality is that of cargo carrying. The Suburban and Yukon XL offer 121.1-ft3 behind the first row and the Tahoe and the Yukon 94.7-ft3. But again, the issue, like that of the doors, is ease of use. So to facilitate the cargo capacity, no longer is the third row seat removed from the vehicle, but it (and the second row) simply fold flat.

Roger McCormack, GMC marketing director, makes a salient point about the full-size SUV segment: the average age of one on the road right now is 11 years old.

Which means that now is probably a good time for GM to be launching a suite of new SUVs.