"GMC's version of the Chevrolet Silverado gets no major changes for 2006 as both trucks await redesigned replacements for 2007. This report covers the half-ton Sierra 1500 and 1500HD models. They comes in regular, extended, and Crew Cab versions. Extendeds have rear-hinged back doors that don't open independently of the fronts. Front seating is via a bench or buckets. Extendeds and Crews include a three-person rear bench seat. Regulars and extendeds offer 6.6- and 8-ft cargo beds. For '06, extendeds are available with the Crew Cab's 5.8-ft bed.
Trim levels ascend from Work to Denali Crew Cab. Denali has all-wheel drive without low-range gearing. Other Sierras are available with rear-wheel drive or one of two 4WD systems. The basic 4WD system should not be left engaged on dry pavement. GM's Autotrac can. Both include low-range gearing. Engine choices range from a 195-hp V6 to a 345-hp V8, depending on model and option selection. Same for available manual and automatic transmissions.
Sierra is also available as a Hybrid model. It's a 6.5-ft-bed extended cab with a V8 and 2WD or 4WD. This uses an electric motor to provide 120-volt power for electrical accessories. However, the electric motor does not propel the vehicle. Its batteries are charged by the gas engine; no plug-in charging is necessary. Sierra's performance and accommodations mirror those of comparable Silverados."

"Motown moles say GM will restyle and reengineer its full-size pickups for 2008. Such wording implies a major makeover, not a total redesign, but a new gas-electric powertrain option is said to be included. Unlike 2005's limited-basis ""mild"" hybrid model, the coming setup uses twin 40-hp electric motors and a 300-volt battery pack to assist a 5.3 V8 with GM's Displacement on Demand. Though even this ""strong hybrid"" system probably won't allow driving on electricity alone, GM expects an economy jump of 30-35 percent for EPA city mileage of around 20 mpg.
The 2008 makeover affects all of GM's full-size pickups and SUVs. Look for Sierra to be differentiated more from cousin Chevy Silverado than has been the case. Powerteams will likely be updated with DOD and perhaps more displacement for some engines."

"Consumer Guide® Automotive places each vehicle into one of 17 classes based on size, price, and market position. Large Pickup Trucks are traditionally the vehicle of choice for heavy-duty hauling and towing. They offer an array of cab styles and bed lengths and usually feature powerful V8 or diesel engines. For personal use, consider light-duty 1/2-ton models. For heavy-duty or commercial use, consider 3/4- or 1-ton models.
Our Best Buys include Chevrolet Silverado, Ford F-Series, and GMC Sierra. Our Recommended picks are Dodge Ram, Nissan Titan, and Toyota Tundra."