Chevrolet's Suburban hit the roads for the first time in 1936, and it's proven itself something of an icon, able to haul and tow just about anything. It was America's first SUV, decades before we knew what that meant. Through the years, the full-size (some would say super-size) platform has been massaged and honed. New sheetmetal, improved powertrains, and increased safety have been applied to the Suburban since Job 1 rolled down the assembly line. But for '03, Chevrolet has slipped an engineering milestone under this big SUV, which changes the future of vehicles this size and turns its competitors into also-rans. It's called Quadrasteer. If you haven't driven an example, your perception of how an SUV should handle will be turned upside down, or at least take a (very) sharp turn.

This system debuted in '02 on the GMC Denali, a premium nameplate that flew below the radar of most enthusiasts. It transformed the pickup truck into a master of tight confines. For '03, this Delphi Automotive Systems-developed technology has been transferred to the 2500-Series Suburban, both 2WD and 4WD models, vehicles with a turning circle charitably described as on a par with the USS Nimitz. Electric motors and a computer control the speed, direction, and amount of deflection according to sensor inputs. At low speeds, the front and rear wheels turn in opposite directions. The result is a dramatic reduction in the turning radius. Last year's 2WD Suburban needed 44.5 feet to create a circle; an '03 Quadrasteer-equipped version requires only 35.2. Driving a 4WD model? You'll use 44.3 feet of parking lot without Quadrasteer; 35 with it. That's only two feet more than a Honda Civic. At moderate speeds, the rear wheels stay pointed straight ahead. Kick up the speed, and both front and rear wheels turn in the same direction. Lane-change stability is impressive, especially when towing. To quote the Delphi press materials: "The positive rear steering reduces the articulation angle between the vehicle and trailer, reducing the lateral forces applied to the rear of the vehicle by the trailer. This, in turn, reduces the yaw velocity gain and increases your damping of the vehicle and the trailer system. The net result is increased trailering stability, reduced trailer sway, and reduced driver corrective steering to external disturbances such as wind gusts, semi-truck passing, and road inputs." In short, the truck/trailer combo feels as one, with none of the tail-wagging-the-dog sensation. Remember, the wheelbase of a Suburban is 130 inches, massive by any measure.

With a turning circle as tight as Quadrasteer allows, care must be taken to prevent jackknifing. Senior Feature Editor and Tow-Master Scott Mead noted that if you "switch off QS, you get the predictable trailer sway that causes hundreds of jackknifes each year."

Hitch a 6800-pound boat and trailer combo on the rear, and the biggest fault of the Quadrasteer 2500-Series Suburban surfaces: lack of power. We aimed our lengthy combo up L.A.'s Grapevine hill, and the five-percent grade took its toll. The accelerator pedal was mashed into the plush carpeting as speed up the grade settled at 43 mph. With a Hydra-Matic 4L80-E four-speed automatic, the tranny stayed in second gear until we reached the summit. The 6.0-liter V-8 is fine if the hitch receiver is empty, but substantial weight results in insufficient performance. It's a pity a larger engine isn't available in the Quadrasteer 2500-Series; the 8.1-liter Vortec, with its 455 lb-ft of torque, would be ideal in this application with a huge trailer or fifth wheel. But to get Quadrasteer, one must order either the LS or LT package. Other equipment requirements include the Vortec 6000 engine, liftgate with liftglass, roof marker lamps, flared rear-wheel openings, limited-slip differential, Heavy-Duty Trailering Package, and Autoride Suspension Package. Items not available with Quadrasteer are the Snow Plow Prep Package or a power sunroof. Chevrolet notes that ordering the Quadrasteer option reduces the vehicle's maximum trailer weight rating by 300 pounds (the weight of the system).

The interior of the Suburban is a grand place to watch the countryside. Tasteful materials and colors create a rolling entertainment center, with a DVD player to keep kids happy, and an excellent audio system that rivals most home setups. Power extend/retract outside mirrors open to a width of up to 106 inches and are a convenience you'll quickly take for granted. Wind noise is conspicuous by its absence (surprising with the large mirrors). One feature many manufacturers have adopted is a driver's-window auto-express up. GM says that, from a safety standpoint, it doesn't make sense to have this feature, but that hasn't been an issue with virtually any other vehicle maker.

Verdict? This fitting of Quadrasteer on the Suburban transforms what was a road-going leviathan with marginal manners into a road-going leviathan that's graduated from charm school. TT