The lone powertrain initially available in the Avalanche is a thoroughly civil 5.3L/285-hp OHV V-8 mated with a sweet-shifting four-speed automatic. And 90 percent of this motor's 325 lb-ft of peak torque is available from just 1600 rpm, which made for some brisk track runs despite the hefty curb weight. The best 0-60 blast took just 8.7 sec.

Fuel-consumption ratings from the EPA are 14/18 mpg for two-wheel-drive versions, 13/17 for four-wheelers (which use the slip- sensing Autotrac system with its computer-operated two-speed transfer case). Later this year, a 2500 Series heavy-duty Avalanche will come on-stream, powered by GM's amazing 8.1L/340-hp 455-lb-ft V-8.

With lots of horses, big payload capability, and relatively high towing capacity, top-notch braking is critical, and fortunately, we found no skimping here. The beefy discs are 12 in. in front and 13 in the rear, with twin-piston aluminum front calipers and ABS all around. Our test numbers at the track showed the effectiveness of the system, with a 142-ft stop from 60 mph. That's pretty good for a vehicle with a 5600-lb curb weight and a gross vehicle weight rating of 6800 lb.

Heavy-duty vehicles don't always nail the details on the interior, with control locations, seat comfort, and convenience features often getting shortchanged. However, the Avalanche makes no apologies. This cab is plenty quiet and the seats are soft but supportive. And the full instrumentation is well laid out and clearly illuminated at night. Most of the controls are nicely located-even for small drivers. The exception is the manual backrest-rake adjustment, which requires a contorted reach.

All occupants (either five or six, depending on front-seat configuration) get lots of crash protection from this beefy piece of transport. Besides the margin naturally afforded by generous crush zones and high mass, the Avalanche offers front and side-impact airbags.

It also boasts an impressively long list of standard features. A sampler: lockable storage built into the top of the bed walls, an overhead-storage console, bumper steps, foglamps, full instrumentation (including tach, voltmeter, oil-pressure gauge, coolant-temp gauge, and engine-hour meter), power steering, power driver's seat, trailer-towing package, tilt wheel, and carpeted floormats.

Originally code-named the Warrior, the Avalanche looks likely to draw some blood in its assault on pickup and sport/utility orthodoxy. This is a new kind of vehicle, and it may change some thinking in the marketplace. If it does, it may also change some other truck maker's product plans.