The key to this truck's versatility is its clever Midgate, which is like having a second tailgate between the cabin and bed. Normally, the Avalanche can carry five adults in comfort and a large amount of cargo in a covered, 5-foot 3-inch indestructible bed. But when you need more space, the rear seats fold down, the Midgate folds forward, and voila! You have an eight-foot bed capable of hauling 4x8-foot sheets of plywood. And your plywood, or drywall, stays dry inside the covered bed, out of the rain. Or take the cover off the bed, remove the rear window and you can park an ATV back there.

As neat as that is, almost equally impressive is the attention to detail seen throughout the Avalanche. Some of the people on the team that designed and marketed the Avalanche spend their weekends fishing, hunting or boating. These folks fully understood the needs of outdoor enthusiasts and they provided for those needs with features such as flush-mounted cargo lights that illuminate the bed, foldaway tie-down hooks, and footholds and handholds for climbing onto the bed. The hard cargo cover over the bed is made of a highly rigid material that can easily support your weight, handy when trying to get things done. We've seen the Avalanche employed by all kinds of people, including building contractors who need the utility of a pickup but want a luxurious cab for passengers.

Avalanche debuted as a 2002 model and was tweaked and refined for 2003. 2004 brought an upgraded braking system. Only trim and equipment changes distinguish the 2005 Avalanche from the 2004.

Avalanche led the way for Chevrolet's edgy new truck styling now seen on the Silverado and Colorado pickups. Still unique to the Avalanche, however, is its extensive lower body cladding, made of a dark charcoal-colored, practically bullet-proof composite designed to protect the rocker panels from years of flying gravel. The cladding has a practical benefit for drivers who spend a lot of time on gravel, but the Avalanche sometimes looks classier without it. We recently glanced at a black Avalanche without the cladding and for a moment mistook it for a Cadillac Escalade EXT, Avalanche's upscale sibling. In other colors, the Avalanche looks cleaner, if a bit plainer, without the cladding. Best of all, it can be deleted for a $600 credit. For 2005, Chevy has released an exterior trim package ($635) for the LS that adds bright accents to the door handles and mirrors, plus stainless steel assist steps, making the base truck look a little richer.

The Avalanche is essentially a modified Suburban; they share about 85 percent of their parts. Like the Suburban, the Avalanche is built on the same superb platform as the Silverado full-size pickup. GM's engineers created the Avalanche by lopping off the rear roof structure and quarter windows of a Suburban, and redesigning the back end. When the Avalanche's rear seats are in place, there's a 5-foot 3-inch bed behind them, which is long enough for most tasks. When that's not enough it converts into an 8-foot bed by taking over the rear seats. Quite an achievement.

The most interesting feature of the Avalanche is the Midgate, which allows this clever conversion. Avalanche has a folding rear seat like a wagon or SUV; the Midgate is essentially a folding bulkhead behind the seat. Flipping the seat bottoms forward and folding the seatbacks down, and then folding down the Midgate, provides flat cargo space and access to the cargo bay behind. Instead of carpet, however, the Midgate is backed with a tough composite material impervious to gravel or anything else you can throw at it.

In fact, the Midgate, tailgate and portions of the cargo box are made from a composite material called PRO-TEC. This material is exceptionally durable, and resists dings, scratches and dents.

But there's more: The rear window of the cab can be quickly removed and stored out of harm's way. The bed cover comes off in three pieces and slides into a nice fabric bag; these pieces attach to the side of the bed to minimize the space they take up. Now you have a fully functional pickup with an open eight-foot bed. You can park an ATV in back, with the front tires and fenders where the rear seat was moments before.

Of course, this results in an open-air driving experience; there's nothing separating you from the open pickup bed. But wind noise is minimal, with no buffeting. We hauled an ATV down dry dirt roads in the high desert of Southern California and minimal dust came into the cab. Only a slight breeze reminds you that your ATV is sitting on the back seat. GM engineers achieved this through extensive tuning in a wind tunnel, and with a pair of flying buttresses that also add structural rigidity to the chassis and can be used as tie-downs.

Alternatively, you can fold down the rear seats but leave the Midgate in place, which creates cargo space inside the cab. There's nearly 54 cubic feet of interior cargo volume with the rear seat folded and Midgate in place.

The bed is protected by a well-designed lockable cover rated to support 250 pounds. You ca.

Avalanche 1500 models ride as well as a fully loaded Suburban. The Avalanche feels smooth, quiet, and tight, with no squeaks or rattles. The suspension soaks up large potholes and rides comfortably on rough terrain.

Hydroboost brakes use hydraulic pressure (from power steering fluid) rather than engine vacuum to decrease brake pedal effort. As a result, the Hydroboost system will continue to provide sufficient power assist to stop the vehicle even if the engine stalls or is turned off.

The 5.3-liter V8 delivers plenty of punch. It's a responsive engine, rated 295 horsepower and, more important, 330 pound-feet of torque. Strong torque launches the Avalanche quickly off the line. Its broad, flat torque curve, with 90 percent of peak torque available from 1600 to 5000 rpm, is designed to provide outstanding trailer-towing and load-hauling capability. A properly equipped Avalanche 1500 is rated to tow up to 8200 pounds.

The 4L60-E four-speed automatic transmission shifts responsively. Pressing the Tow/Haul button results in quicker, harder shifts and reduces heat by limiting the amount of hunting between gears.

The 4WD model's Autotrac transfer case lets the driver select different drive modes for different conditions: 2HI drives the rear wheels only and offers the best fuel efficiency. Auto 4WD transfers power from the rear wheels to the front wheels as needed to optimize traction in inconsistent conditions. 4HI provides the best traction in rugged terrain. 4LO is available for when the going gets really ugly. A neutral position allows the Avalanche to be flat-towed.

2WD 1500 models offer StabiliTrak ($750) electronic traction and stability control. The traction-control function allows acceleration without wheel spin on slippery surfaces. The stability-enhancing function maximizes handling and braking on a variety of surfaces, and is particularly advantageous in slippery corners. An array of sensors monitor steering wheel angle, wheel speed, brake pressure, longitudinal and lateral acceleration, and yaw rate; a computer uses the data to compare the driver's intentions with the actual direction the truck is headed. The system is programmed to allow for intervention thresholds, but above that point it steps in whenever one or more wheels is slipping or if the vehicle is slipping sideways or if it is understeering or oversteering. StabiliTrak adjusts engine torque or the brake pressure to individual wheels to help steer the truck back to the path the driver intended. Our advice: If you opt for 2WD, order StabiliTrak.

Multi-zone manual climate control is standard on all models. An automatic battery-protection system shuts off the lights 10 minutes after you turn off the ignition.

Optional power-adjustable pedals move up to 3 inches closer to the driver. That's a real boon for shorter drivers, who won't have to sit as close to the steering wheel in order to reach the pedals. Because the airbag is mounted in the steering wheel hub, the adjustable pedals become a safety feature for women of average height or shorter. The adjustable pedals have a memory function, adding convenience for mixed-height couples.

Avalanche comes with a six-speaker CD stereo, and you can order premium Bose speakers and a six-CD changer. XM Satellite Radio is a real feature when traveling because the stations don't change as you drive across the country and you can stay in touch by listening to FoxNews, CNN and other 24-hour news and sports stations. It's nice to have around town for listening to your favorite music (rock, country, classical, '50s, '60s, '70s, '80s, whatever).

The optional rear-seat video system includes a DVD player with a flip-down screen to keep munchkins entertained on long journeys. It comes with two sets of wireless headphones, auxiliary audio/video jacks, a remote game plug-in, separate audio controls for the rear compartment, and a mute button.

OnStar is well worth having for safety, security and convenience. It works well as a navigation system and there's nothing to program: Simply press the blue button and a human operator responds through a speaker, ready to provide directions and other assistance. OnStar always knows the location of your vehicle. The staff will notify authorities of your location if your airbag goes off and you do not respond to their calls. Or you can press the emergency button and they'll send out the troops. They can unlock your doors if you lock your keys inside. They can direct you to the nearest gas station or help find a good restaurant or motel. If your vehicle is stolen, OnStar can pinpoint its location and direct the authorities to apprehend and recover.

There's plenty of power from the 1500 model's V8 engine. Ride and handling are excellent. The heavy-duty Avalanche 2500 offers big towing capability. Attention to detail is impressive, both in design and engineering and in customer comfort and convenience. Overall, this is one of the most interesting trucks available today.