BIGGEST LAUNCH EVER? GM says its 2007 full-size trucks are critical to the company's success.(News)

Byline: WES RAYNAL

They won't be the biggest sport/utility vehicles ever introduced, but General Motors officials concede the company's all-new 2007 full-size SUVs are huge when it comes to GM's future. Officially, GM insists the trucks won't make or break the company, but privately they say failure is not an option.

The trucks, pushed ahead in development to help shore up GM's bottom line, have all-new sheetmetal, new engines, new chassis and suspension, and new interiors. GM says they offer more power and better fuel economy than the vehicles they replace.

The Chevrolet Tahoe, GMC Yukon/Yukon Denali and Cadillac Escalade go on sale early next year, followed by extended-wheelbase versions, including Chevy Suburban and Avalanche, GMC Yukon XL and Yukon XL Denali, and Cadillac Escalade ESV and Escalade EXT by mid-year. GM is mum on prices.

The new range of V8 engine offerings includes a base 290-hp 4.8-liter; two 5.3-liters (one aluminum block and one iron block), with Displacement On Demand making 320 hp; a 6.0-liter heavy-duty with variable-valve timing, 350 hp; and another 6.0-liter with both Displacement On Demand and variable valve timing good for 355 hp. At the top of the range is a 6.2-liter with variable valve timing in 380- and 400-hp versions.

Chevy Silverado and GMC Sierra pickups follow the SUVs to market later in 2006, with diesel and E85 (ethanol and gasoline mix) flex-fuel engine offerings. Hybrid technology comes to the trucks in 2007, with a two-mode system with electric motors built into ...