Performance We like the 5.3-liter V8 best, but the 4.8 handles most light-duty chores just fine. Fuel economy isn't so fine. We averaged just 13.6 mpg with an automatic 5.3-liter extended-cab 4x4.
   The automatic's Tow/Haul mode and Sierra's optional adjustable suspension are welcome features, however, since 70 percent of big-pickup buyers haul or tow at some point. Brakes offer a firm feel and progressive pedal action, while steering is precise despite too much power assist. Ride quality is good for a big pickup, but the usual empty-bed tail jitter can occur over bumps. Road, wind, and engine noise are not objectionable.
   Accommodations Sierra follows Silverado with gauges and controls that are best in class for design, feel, and location. We also like the engine-hour meter that supplements the usual mileage odomter. All models have roomy and supportive front seats with handy integrated safety belts that are always comfortably positioned. However, drivers with thick forearms will have trouble squeezing between the door panel and seat to reach the adjustment controls.
   GMC (Chevy too) has finally caught up with Ford and Dodge in the extended-cab "door race", and its doors not only open wide but have robust exterior pull handles instead of slip-prone flippers. A standard spare-tire lock is another plus. GM's big extendeds also soundly trouce rivals for rear leg clearance and boast a contoured rear bench seat with reclined backrest that provides almost sedanlike comfort.
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