The Specs:

GMC SIERRA DENALICHEVROLET SILVERADO 1500 REGULAR CAB WT
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
BLOCKAluminumIron
TRANSMISSIONSix-speed automaticFour-speed automatic
DRIVELINEAWD RWD
EPA FUEL ECONOMY13/19*16/20*
WHEELBASE (IN)143.5119
BED LENGTH5 ft, 9 in6 ft, 6 in
PAYLOAD (LB)1,7191,952
MAXIMUM TRAILERING CAPABILITY8,5008,200
*2007 Figures

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.

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.