When it comes to engine options, the 2007 GMC Sierra has the market pretty much smothered. Regular Cab models come with a standard 4.3-liter, 12-valve V6 offering 195 horsepower at 4,600 rpm and 260 lb.-ft. of torque at 2,800 rpm. Should more power be desired, a 4.8-liter, 16-valve V8 provides 295 horsepower at 5,600 rpm and 305 lb.-ft. of torque at 4,800 rpm. However, this is a Professional Grade truck, meaning the typical Sierra buyer may be most interested in the available 5.3-liter, 16-valve V8 pushing 315 horsepower at 5,200 rpm and 338 lb.-ft. of torque at 4,400 rpm. This final engine choice features GM’s Active Fuel Management technology, designed to cut power to four cylinders when appropriate for improved efficiency, and can be ordered in gas-only or gas/E85 (ethanol) versions.

Extended and Crew Cab variants of the 2007 GMC Sierra add an optional 6.0-liter, 16-valve V8 boasting 367 horsepower at 5,500 rpm and 375 lb.-ft. of stump-pulling torque at 4,300 rpm. The Crew Cab Denali ups the ante even more, using a 6.2-liter, 16-valve V8 to crank out 400 horsepower at 5,700 rpm and a very respectable 415 lb.-ft. of torque at 4,400 rpm. Both engines feature variable-valve timing, yet lack Active Fuel Management technology.

With the exception of the Denali, which includes a six-speed automatic transmission, all Sierras use a four-speed automatic to deliver power to the rear or all four wheels. Again, the Denali differs by offering rear- or all-wheel drive, whereas other Sierras are either rear- or four-wheel-drive. The track has been widened (3.2 inches up front, one inch out back) for better stability, the fully-boxed frame strengthened, an all-new front subframe added, and tires measuring 17 to 20 inches are directed by a hydraulic rack-and-pinion steering system. The 2007 GMC Sierra rides on a new suspension system comprised of coil-over springs in front and a Hotchkiss-style live axle with leaf springs under the bed. Rear shocks have been mounted at an angle to improve ride quality and handling. Five suspension packages are offered: Z83, the basic setup; Z85, designed for improved handling and towing; Z71, the so-called off-road option; Z60, the street setup with available 20-inch wheels; and the NHT package for the hardcore tow junkie.

Weighing in between 4,450 and 5,300 pounds, the 2007 Sierra can accommodate a payload up to 2,160 pounds (Extended Cab Short Box 2WD) and carries a maximum tow rating of 10,500 pounds (Extended Cab Short Box 4WD with 6.0-liter V8 and 3.73 axle; Crew Cab 4WD with 6.0-liter V8 and 4.10 axle). The bed is 1.18 inches deeper up front and 1.57 inches deeper by the tailgate.