It can't be easy to motivate an engineering team to redesign and improve a vehicle that dominates its market segment as thoroughly as the GM full-size SUVs do theirs. Chevrolet's Tahoe/Suburban and GMC's Yukon/XL/Denali utes gobble up a greedy 74 percent of the market. If combined as a single brand, these 'utes would rank 19th in sales. They even trump their domestic and offshore competition in J.D. Power Initial Quality and Dependability rankings. So formidable are these trucks, that, while the Suburban celebrates its 80th birthday this year, word on the street has it that Toyota may drop its Sequoia in '17, and Nissan its Armada in '16, despite the fact that, for the last five years, this segment's transaction prices have outpaced the market, increasing by 25 percent versus 9 percent (with the big GM 'utes currently matching Audi's brand average transaction price).

So with "don't-screw-it-up" as their likely directive, the team set about upgrading the GMT900 trucks to the new K2 truck architecture that debuted with the 2014 full-size pickups. That means they get the EcoTec3 engines -- displacing 5.3 liters for all Chevys and base GMCs, 6.2 liters for Yukon Denali models -- and 6L80 six-speed automatic transmissions. Preliminary output specifications match those of the pickups (355 hp/383 lb-ft and 420 hp/450 lb-ft). Their fully boxed frames are now 75 percent high-strength steel, and an inch-wider rear track and half-inch wider wheel rims improve cornering stability. Steering assist is now electric, Duralife corrosion-resistant brake discs are fitted at all four corners, and magnetic shocks smooth the ride of the top models. A locking 9.5-inch rear differential is now standard.

Styling revisions are evolutionary, but perhaps less so than with the pickups, with which these 'utes share no visible sheetmetal. Like the pickups, however, the doors are inset flush with the bodyside for improved aerodynamics and reduced wind noise, and the door openings and pillars are reshaped to ease entry and egress -- especially to the third seating row. There's no mistaking the more prominent new body shoulder line or the aerodynamically significant rear airfoil, which forms a prominent shelf over the rear lift-glass, and conceals the rear wiper up off the glass. Other touches borrowed from the (now retired) Tahoe Hybrid include the front air dam and a crease on the C-pillar that helps separate the airflow. The entire front clip is differentiated between Chevy and GMC brands, the hood is aluminum, as is the liftgate, which offers programmable height limitation and power screw-jacks that consume less interior space than the old gooseneck power mechanism. Foglamps and projector low-beam headlamps and are now standard, with HID illumination on top LTZ and Denali models.

Inside the biggest news is the that the heavy, clunky, removable third row seats have been ditched in favor of a fold-flat design with optional power folding that forms a level surface with the folded second row and with a false floor in the back, which can conceal small items like jumper cables. This advance comes at some cost to total cubic capacity, which drops from 137.4 to 121.1 cubic feet on Suburban/XL models and from 108.9 to 94.7 on shorty Tahoes and Yukons. The second row boasts nearly 2 inches more legroom, and front row gets a center side-impact airbag to separate front-seat occupants (except on fleet models with the bench seat).

All the latest safety and comfort tech is here now -- lane-departure and forward-collision warnings, blind-zone assist, adaptive cruise control, and passive entry and starting. The new cabin offers storage crannies galore, and a dozen device charging ports, including one 110-volt plug and up to six USB ports. Blu-ray entertainment is offered, but without an HDMI input. A 4.2-inch infotainment display is standard, with an 8-inch screen option bringing MyLink/IntelliLink apps and concealing a "safe" in compartment. Optional power-folding running boards with perimeter lighting ease entry/exit. And we're promised these will be the quietest big 'utes on the market, thanks to triple sealing on the inset doors, additional sound dampening materials, and acoustic laminated windshield and front-door glass on top models, and (on Denalis) active noise cancellation though the Bose Centerpoint stereo. There's even a panoramic "conversation mirror" to allow the driver to monitor all rows, for those who miss that feature from their old Windstar minivans.

These new K2 'utes promise to deliver more of pretty much everything you liked about the GMT900s while sipping a tad less fuel, so it's hard to imagine market share slipping, unless Ford has amazing plans for the 2016 Expedition.

Denali Spotters' Guide:
Unique styling touches distinguishing the Escalade-adjacent GMC flagship include the chrome perforated-metal-look grille, HID lamps, LED running lights, 22-inch chrome wheels, and chrome flourishes on the liftgate and rear bumper. Inside, there's a standard head-up display, and suppler Mulan leather replaces the Yukon's quotidian Meridian hides.

Learning K2 Lingo
Down at the pub, you'll want to refer to that new base Tahoe/Yukon you just picked up as a C-15-7-06 and your buddy's HD 4WD Suburban as a K-25-9-06. Here's how it breaks down: C or K for RWD or 4WD; 15, 25, or 35 for half-, 3/4-, or 1-ton; 7 for short-wheelbase, 9 for long-wheelbase; 06 for SUV. Want to talk pickups? In place of that 7 or 9, put 6 for a 5-foot box, or 9 for an 8-foot box; and in place of the 06 SUV designator, put 03 for regular cab, 43 for crew cab, or 53 for double-cab.


2015 CHEVROLET TAHOE/SUBURBAN GMC YUKON/XL/DENALI
BASE PRICE $43,000-$64,000 (est)
VEHICLE LAYOUT Front-engine, RWD/AWD/4WD, 5-9-pass, 4-door SUV
ENGINES 5.3L/355-hp (est)/383-lb-ft (est) OHV 16-valve V-8; 6.2L/420-hp (est)/450-lb-ft (est) OHV 16-valve V-8
TRANSMISSION 6-speed automatic
CURB WEIGHT 5350-6000 lb (mfr)
WHEELBASE 116.0-130.0 in
LENGTH X WIDTH X HEIGHT 203.9-224.4 x 80.5 x 74.4 in
0-60 MPH 7.2-8.5 sec (MT est)
EPA CITY/HWY FUEL ECON Not yet rated
ON SALE IN U.S. Spring 2014