SLT 4x4 Extended Cab 6.6 ft. box 143.5 in. WB
2008 GMC Sierra 2500HD Reviews

2008 Sierra 2500HD New Car Test Drive


GMC Sierra heavy-duty pickups are well-suited for real-world use and abuse. They can haul tons of brick and cement and tow the mixer, then turn around to be used for a night on the town or grocery shopping while the fifth-wheel's left in camp or the horses are in the corral. The Sierra HD models are the mid-level part of GMC's truck lineup, so if your hauling happens once or twice a year, or you tow a bass or ski boat, the 1500-series is better-suited; conversely, if you've got a mammoth trailer to pull, step up to the Kodiak/Top Kick medium-duties. 

The GMC Sierra HD pickups were thoroughly redesigned for 2007, so changes for 2008 are limited to smaller items like seat adjusters, gauges, and adding XM Satellite Radio capability. 

The GMC Sierra HD offers styling unique to GMC, so it's not just a Chevy Silverado with a different grille. 

As with all heavy-duty pickup lines, the Sierra HD offers plenty of configurations with three cab sizes and two bed sizes in 2WD or 4WD. But it also offers two separate interior concepts, something the other guys can't match. And GM offers the only HD pickup with a six-speed automatic as standard (an option only on the Dodge Ram diesel). Its standard 6.0-liter gas V8 is rated higher than anyone else's, as is the 6.6-liter diesel. And only GM includes OnStar as standard. 

Almost everything you can get in a GMC sport-utility is available here, including a subwoofer-equipped sound system, navigation, driver memory system, heated leather seats (and heated windshield washer fluid) and a moonroof. At the other end of the spectrum, for the entry price of around $24,000 you get a functional pickup with real load-carrying ability and all the safety bits of the top-line model. 

The trick in buying a GMC Sierra HD is to give fair consideration and choose wisely. Compute the permutations among three cabs, two weight classes, two beds, two engine/transmission combinations, two drive systems and four trim levels, and then sort out options that cover everything from a diesel radiator cover to rear park assist, and you can see why prices run from that base $24,000 to well past double it. 


The 2008 GMC Sierra HD comes in three cabs (Regular Cab, Extended Cab, Crew Cab) and two weight classes, 2500 HD and 3500 HD, all with 2WD or 4WD. The 2500 (sometimes called 3/4-ton) offers two pickup box sizes, while the 3500 (1-ton) is eight-foot box only. If you wish to add your own utility box or flatbed, cab and chassis models are offered. 

GMC nomenclature labels trim levels as commercial-grade Work Truck, popular SLE (1 and 2), and premium SLT that resembles a Yukon sport-utility up front. 

Basic WT fare includes a split vinyl bench seat (and split rear seat on four-door cabs), stereo radio with XM satellite, air conditioning, six-speed automatic transmission, tire pressure monitors, and ABS. 

Mid-level SLE models include all basic equipment and add cruise control, chromed steel wheels, electronic shift for 4WD, auto-dimming mirror and compass, driver lumbar, locking seat cushion storage, and leather-wrapped steering wheel. The SLE2 package adds fog lamps and interior upgrades such as cloth-upholstered power-adjustable front seats and redundant controls on the steering wheel. 

SLT badges are reserved for the priciest Sierras, those with an interior modeled after GMC luxury utilities. These include as standard leather upholstery with 12-way power and heated front seats, two-person driver memory, heated windshield washer fluid system, locking differential, remote start, towing package, 17-inch aluminum wheels, and a Bose audio system with subwoofer. 

Base power for all GMC HDs is the latest 6-liter V-8 with an iron block for durability and variable valve timing for efficiency; it rates 353 hp and 375 lb-ft of torque (312 hp for GVWR above 10,000 pounds). The sole option is a 6.6-liter Duramax turbodiesel, at 365 horses and 660 lb-ft of torque. A six-speed automatic is the only transmission offered, and on diesels it adds $1,200 to the engine's roughly $7,200 tab. 

Sierras can be set up for anything from a night on the town--moonroof, satellite radio, navigation--to a year on the ranch or fleet garage with snow plow prep, integral trailer brake control, remote start, and power takeoffs. Determining exactly the right model and options will take careful and honest shopping because of the sheer number of choices. 

Safety equipment includes frontal airbags, front seat belt pretensioners (a first for HD pickups), ABS, and OnStar. 

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