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2008 GM Trucks - From Top To Bottom

Driving The '08 GMC Sierra Denali And Chevrolet Silverado 1500 WT

Rex Roy
Nov 1, 2007
Photographers: General Motors, Rex Roy
Just the idle of the 403hp 6.2L V-8 is enough to make you fall in love. The cam gives it a mildly lumpy burble that's tuned to resonate like the low notes of some Gothic organ. Matching this sound perfectly is deep piano-black paint. It's classy but a bit menacing. Meet the '08 GMC Sierra Denali. It's the most expensive light truck to wear the GMC name, and the most powerful, too. Optioned out, this truck stickers for almost $48,000.
Photo 2/13   |   It's the same motor you'll find under the hood of Cadillac Escalades, but you can't get it in any other pickup. It makes great noises and makes this truck move out with authority.
At the other end of General Motors' truck spectrum is the Chevrolet Silverado 1500 WT. In the regular-cab Work Truck (WT) form, it is GM's least expensive fullsize truck with a list price of around $18,000. Our tester, a two-wheel-drive model with just a few choice options, came in at about $21,000. While nothing fancy, it is a truck you could love, too, just for different reasons than the Denali.
Before driving these two trucks back to back, we went into this driving face-off seeking answers to some of our questions: Is any truck really worth $48,000? Would anybody want to drive the cheapest Chevy pickup? Do these trucks share too many components and feel too much alike? Read on for the answers.
Starting At The Top
When you look at the spec sheet, the Denali could easily pose as a sports car, until you get to the dimensions of the bed and its payload capabilities. Here are the facts: It has 403 hp, 417 lb-ft of torque, a six-speed gearbox, full electronic stability controls, four-wheel disc brakes with the latest Bosch ABS, 18-inch rims, short 3:42:1 gears, an Eaton automatic locking differential, and a robust 9-1/2-inch rear axle. Clearly, this is the hot rod of the GM truck family. But, unlike some past hot rod trucks-remember the GMC Typhoon that had a towing capacity of only 900 pounds-this truck can work like a truck. The 5-foot 9-inch bed can handle more than 1,700 pounds, while it can tow a full 8,500 pounds.
You Have Arrived
Inside, you could easily mistake the interior of this truck for a luxury car. The overall design is high-end, and the trim panels fit tight. The leather on the seats looks and feels good. The wood on the steering wheel adds a rich touch. The Denali manages this high degree of elegance, while being tasteful, accommodating, and useful. For those of you who have been in onem of GMC's new Yukon Denali SUVs, you'll recognize where GMC pulled these nice pieces. Most everything comes from the SUV cousin, including the supportive front bucket seats, the functional center console, and airbags coming at you from the front, the sides of your seats, and down from the roof header. Our only hit on the interior is the cheap-looking bezel that goes around the radio. In an interior this nice, the cheapo stuff has to go.
Photo 3/13   |   2008 Chevrolet Silverado rear Passenger Side View
Since the Denali is a sedan truck (a four-door), we spent some time evaluating the rear seating area. It's big back there, and adults should have no problem getting comfortable. Ours even had the factory-installed DVD entertainment system. When you're hauling cargo and not people, the rear seat cushions simply fold up against the backrest-no buttons to push or latches to release-simple, just as it should be.
Premium Power
As already noted, power comes from the Denali's 6.2L Gen IV smallblock engine. It's the same motor you'll find under the hood of Cadillac Escalades, but you can't get it in any other pickup. It makes great noises and makes this truck move out with authority. The torque is great, and the power just keeps coming right on up to the 6,000-rpm redline.
The Denali comes in rear-wheeldrive and all-wheel-drive configurations, and our test truck was the latter. Getting off the line in a hurry took nothing more than brake-torquing the motor and sidestepping the brake. The big Goodyear Eagles immediately hook with no wheelspin. You end up at 60 mph in less than 7 seconds. Remember, this truck weighs more than 5,300 pounds, so there's some real hustle coming from under the hood.
The smooth-shifting six-speed automatic sports twin Overdrive gears with Sixth being a super-tall 0.66:1 for effi cient and quiet cruising. While we liked the way the engine and transmission worked together most of the time, when you try to settle into an 80-mph interstate cruise, the transmission hunts for the right gear. When climbing even a slight grade, the unexpected Sixth to Fifth downshift is jarring, and it seems that with the engine's torque this shifting is completely unnecessary.
High-End Ride
We learned more as the miles tallied up. You can run this truck hard. The giant 275/55R20 tires deliver a lot of grip, so the Denali feels stable as it responds quickly to commands from the steering wheel, but there's not a lot of road feel. While the ride was firm for those up front, it was completely comfortable. However, our female test participants complained that the ride in back made them want to put on a sports bra because of the bounce. Upon hearing these comments, we did a quick back-to-back with a currentgeneration Ford F-150 Crew Cab and found that the Ford's ride did exhibit less boob bounce.
Another issue surfaced because of the beat-up strips of broken concrete that pass for roads around Detroit. The optional 20-inch chrome rims that were on our tester certainly look great, but compared to the Denali's standard 18-inch doughnuts, the larger wheel/tire combo delivers sharp inputs to the suspension that make their way into the otherwise quiet cabin. If ride quality matters to you, go with the smaller-diameter wheels. And based on our recent experience, driving an '07 Cadillac Escalade (also based on the GMT900 chassis), definitely stay away from 22-inch rims, as the ride was considerably worse with that option.
Photo 7/13   |   2008 Chevrolet Silverado passenger Side View
The Other Side Of The Tracks
The Chevrolet Silverado 1500 WT may have come from the same family tree as the GMC Sierra Denali, but the two branches must have been far from each other.
The silver-blue paint and steel wheels on our regular cab tester helped our imagination visualize magnetic door signs spelling out Bob's Construction or Bill's Plumbing. The workman-like feeling continued when we opened the driver-side door.
Our Silverado had a more rugged, work-oriented interior, compared to the Denali. Beyond the radio and seatbelts, you'd be hard-pressed to find shared pieces. The split bench seat is covered in soft but durable cloth. It could easily sit three across. The windows had cranks, not electric switches. The dash covering was durable vinyl with not even a hint of wood, real or fake. All of the controls were designed to be operable even with a gloved hand. This is a refreshingly simple interior that reminded the author of what trucks used to be like-designed for doing work and not much else.
Photo 8/13   |   2008 Chevrolet Silverado rear Drivers Side View
Our first thought was that the interior would not be as comfortable as the Denali's, but this impression was incorrect. On the road, the bench provided a good seating position and reasonable support. What truly surprised us was the quietness of the interior. Because of the truck's aerodynamic exterior and extensive insulation and sealing, there is almost no wind noise. Road and engine noise are also suppressed.
A downright supple ride complemented the hushed interior. Unlike some live-axle trucks, the Silverado exhibited no axle hop under any circumstances we encountered. The rear end stayed planted, even over expansion joints at highway speeds.
One of the few options on our Silverado was the 4.8L V-8. Matched to a mundane Hydramatic four-speed automatic transmission and a shorterthan- stock 3.73:1 rear axle, the engine's 295 hp moved this 4,400 pounds briskly. The truck never felt slow, although the Denali would have blown its tailgate off because of its better power-to-weight ratio.
The Specs:
ENGINEVortec 6.2L V-8 Vortec 4.8L V-8
HORSEPOWER403 at 5,700 rpm295 at 5,600 rpm
TORQUE (LB-FT)417 at 4,300 rpm305 at 4,800 rpm
TRANSMISSIONSix-speed automaticFour-speed automatic
EPA FUEL ECONOMY13/19*16/20*
WHEELBASE (IN)143.5119
BED LENGTH5 ft, 9 in6 ft, 6 in
PAYLOAD (LB)1,7191,952
*2007 Figures
Photo 12/13   |   2008 Gmc Denali front Passenger Side View
Understanding The Family Tree
The GMC and Chevy are both based on GM's new-for-'07 GMT900 chassis. Introduced late in the summer of 2006, the all-new trucks ride on a stronger chassis with a fully boxed frame that is 234 percent stronger (torsionally) and 62 percent stronger (vertically), compared to the previous GMT800 trucks. This is critical, because when the chassis is solid, it can handle more power, the suspension can be tuned better, the vehicle is quieter, and the feeling of quality improves. Also, payloads and towing capabilities go up.
Suspensions under all GMT900s are also new. For added stability, the front track is widened 3 inches. Monotube shocks with coilover springs, once only used on sports cars, are now standard fare up front. In back, there is an additional inch of track width. Traditional leaf springs keep the live rear axle in place because, apparently, GM truck engineers believe that real trucks don't wear coil springs in back. The tried-and-true leaf design features important refinements such as splayed shocks and new mounting points. The standard wheels are 17-inchers, with 18- and 20-inch rims available.
Powering the new trucks are engines that consist of high-performance V-8s and a lone V-6. The 5.3L and 6.0L V-8 engines include active fuel management, a feature that shuts down fuel delivery to four cylinders, helping increase mileage in light-load driving. The most advanced motors, like the one in our tester Denali, use technology developed for the Corvette Z06's LS7 engine. The aluminum heads are a high-flow design with unique inlet port and offset rocker arms. The 6.0L and 6.2L engines also include variable valve timing (VVT), a trick system that automatically changes the phase of the cam to alter intake and exhaust valve timing. VVT is key to maximizing idle smoothness and allows the engines to make more power over a wider rpm range.
Photo 13/13   |   2008 Gmc Denali drivers Side View
Of course, the styling of the trucks is also all-new. Unlike past generations, there are genuine differences between the GMC and the Chevy-it's not just a grille and badge deal. Check out the headlights, hoods, and fenders to see the styling cues unique to each model. And when you look closely, you'll start to see the improved quality of the trucks. The body gaps are tight and even, especially when you look at the gap between the bed to the cab and the bumpers to the body. While this introduction doesn't answer any of our questions, it does give you the goods to better understand these two trucks.
The Final Word
During two weeks of driving that covered nearly 1,000 miles, we learned some things. Most certainly, the base Silverado is a great driving truck and a genuine value. Priced competitively against many economy cars, it's easy to understand why Chevrolet sells so many 1500s.
A harder question to answer is whether the Denali is worth two-plus Silverados. Our answer is that if you can afford a $48,000 truck, then assessing worth doesn't matter.
Lastly, while the trucks share many body and chassis components, General Motors did an excellent job of differentiating the individual models. This is critical, because GM sells nearly 1,000,000 pickups per year, and you can't sell the exact same truck to everybody. As our comparison proved to us, there's plenty of choice from top to bottom.


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