PHOENIX – This is the big one for General Motors Corp.

The '07 Chevrolet Tahoe is the first of the GMT900 family of fullsize trucks to hit the streets, and it needs every bit of its increased dimensions and high-strength steel.

The load – expectations of maintaining high-volume sales and profits – is so crucial that GM accelerated development of this mega-platform.

The first GMT900-based SUV, the Tahoe, began salable production in Arlington, TX, Dec. 1, six weeks ahead of schedule. It is followed this month by the GMC Yukon and the ode to bling, the new Cadillac Escalade.

’07 Chevrolet Tahoe

The GMT900 fullsize pickups are on track for launch 13 weeks ahead of schedule, in fourth-quarter 2006.

Any fears a rush job would jeopardize the quality and performance of the new trucks are put to rest in test drives here.

The Tahoe ambitiously shoots to deliver satisfying performance and improved fuel economy, and arguably achieves both goals.

GM's Gen IV small-block 5.3L OHV V-8 generates 320 hp and 340 lb.-ft. (470 Nm) of torque and gives the 4-wheel-drive Tahoe capacity to tow up to 7,700 lbs. (3,492 kg).

The standard Displacement-on-Demand (DOD) technology shuts down four cylinders when not needed for what should be as much as a 25% improvement in fuel economy, GM engineers say.

In test drives, cylinders shut down and return to duty seamlessly. The instrument panel's driver-information display thoughtfully provides a constant update of how many cylinders are at work at any given time.

The auto maker concentrated on making the new SUV more aerodynamic, as well. Contributing to the overall sleek look is a more steeply raked windshield, sloped at a 57-degree angle vs. 50 degrees on the outgoing model.

Gary White, the 6-ft., 4-in. (1.9-m) vehicle line executive for fullsize trucks, says the new angle improves visibility for tall occupants. Sun visors tuck into a sculpted headliner further aid the sight line.

Even the lip for the fuel-filler door was removed to keep unnecessary protrusions out of the airflow.

The payoff: Wind-tunnel testing confirms a best-in-class 0.363 coefficient of drag.

The efforts combine for fuel economy of 16 mpg (14.7 L/100 km) in city driving and 22 mpg (10.7 L/100 km) on the highway for the 2-wheel-drive model.

GM says the fuel-economy ratings not only retain best-in-class status for fullsize utilities but also exceed the performance of about a third of the midsize SUVs on the market, many of which use V-6s.

Additional efficiency will come midyear in the form of a 4.8L variant of the small-block V-8 for the 2WD LS trim.

The new trucks also were designed to run on E85 fuel, a blend of 15% gasoline and 85% ethanol. This capability is standard on 4-wheel-drive models and optional with 2WD.(See related story: GM to Spotlight E85 Capabilities )

The 5.3L V-8 has little trouble propelling the 5,233-lb. (2,374-kg) Tahoe, but there is the occasional hesitation from the carryover 4-speed automatic transmission.

GM's new 6-speed automatic will debut in the Escalade and probably follow on the Yukon Denali. Officials say it will be some time before it appears in the Tahoe family.

On the breathtakingly narrow and winding Apache Trail that travels 28 miles (45 km) to Tortilla Flat, the rack-and-pinion steering is tight; the vehicle nimble; and the larger disc brakes (13-in. [33-cm] front and 13.5-in. [35-cm] rear) smooth as silk.

The upgrade from the mushy brake pedal on the outgoing model is an oasis on this often single-lane desert drive.

The new truck's on-center steering feel makes for effortless driving on the straight stretches, where wind ripping up the canyon from the Gulf of Mexico does not buffet the sturdy Tahoe or sap the driver's energy.

The Tahoe boasts a new and stiffer fully boxed frame. It has a new independent coil-over-shock front suspension and 5-link solid-axle rear suspension, with a real-time damping system that all but eliminates body roll.

Add to that wider front and rear tracks, a lower center of gravity and 17-in. standard wheels that can be bumped up to 20 ins. – the Escalade will have optional 22-inchers – and this SUV enjoys admirable stability and handling, not to mention precise cornering.

Generally speaking, it "drives small," which was one of the biggies on GM's checklist of driving-dynamics priorities for the all-new platform.

The aspirations for the interior were equally daunting. But there, the vehicle had to feel big.

GM stuck its neck out with advance hype about interiors being the battleground of the future. For the GMT900, the auto maker amassed the troops on all fronts.

Material selection is a vast improvement, with a combination of wood, aluminum and leather.

The rat-fur headliner of the old Tahoe has been replaced with textured material; the miles of plastic on the instrument panel are tasteful; and detail touches include a splash of aluminum on the sill plates. Marks for fit and finish, on the whole, are high.

The center console is clean and simple. Buttons look small but are well arranged and easy to operate. Controls for heating and cooling are refreshingly intuitive. Directing heat from a particular vent is as easy as pushing the appropriate button – no toggling or mode-searching involved.

The switch for the adjustable foot pedals is not a gorilla's reach but more logically positioned in the center stack.

The storage bin between the driver and passenger doubles in size to 1,220 cu.-ins. (20 L) of capacity.

Then there is the seating. The new seats are thinner and constructed of higher-density foam. White is particularly proud of the 41.3 ins. (105 cm) of legroom for the driver. The seat backs are sculpted to give second-row passengers an extra half-inch (1.2 cm) of legroom as well.

The star of the interior is the segment-exclusive power fold-and-tumble second-row seating for easier access to the third row. When flipped up, the exposed seat back is smooth and guaranteed not to snag anything.

It was, in part, the 6-door Suburban concept of a few years ago that helped clarify customers need easier access to the third row but not necessarily with another set of doors, White says.

First- and second-row seats are heated. Third-row seats are easily removed and carried off with a handle, like a suitcase.

Additional available features include a touch-screen navigation system, rear parking assist and rearview camera, DVD rear-seat entertainment system and heated window- washer fluid.

Power-articulating running boards will become available midyear.

GM also aimed for the quietest interior in the segment, knowing the engine's DOD technology creates a noise, vibration and harshness challenge when the V-8 operates in 4-cyl. mode.

Damping materials were sprayed on the dash, floor panel and in sound paths throughout the vehicle. Noise-reduction efforts also were employed in the headliner, door seals, engine cover and alternator, while the exterior mirrors and roof rack were streamlined, all in an attempt to reduce noise 20%.

On both pavement and dirt roads, the cabin maintains a notable quietness.

On the safety front, GM expects 5-star crash ratings when the Tahoe is tested, helped by additional crush space with the new front frame design and straightened rails.

Dual-stage airbags are top-mounted, and there are roof-mounted head-curtain side airbags with rollover protection for all three rows of the 9-passenger vehicle.

As the Tahoe arrives in dealerships this month, GM expects the base LS model to account for 10%-15% of sales, and the top-of-the-line LTZ should net 20%-25% of total deliveries. The bulk of the volume should be the three versions of the LT trim level.

The always-popular Z71 off-road package will be added to the mix by the third quarter.

Yes, the load the Tahoe must bear is huge. But the early assessment suggests the new SUV has what it takes to hit pay dirt.Â

apriddle@primediabusiness.com