GM is phasing its 2-Mode Hybrid system into more and more vehicles, and GMC's Sierra full-size pickup is next up on the transformation list. Also unveiled at the 2008 Chicago Auto Show was the Denali XT Hybrid Concept.

2009 GMC Sierra 2-Mode Hybrid

2008 Chicago Auto Show
2009 GMC Sierra 2-Mode Hybrid

2008 Chicago Auto Show
2009 GMC Sierra 2-Mode Hybrid

Sierra Hybrid comes in rear- and four-wheel drive versions with only one body style and one powertrain: a crew cab with a 5.8-ft bed and 6.0-liter V8 with Active Fuel Management and Electrically Variable Transmission. The last is part of the 2-Mode Hybrid system and works in conjunction with an electric motor and 300-volt nickel-metal-hydride battery pack. The combination allows the gas engine to shut off when the truck is stopped, and under light throttle, GMC says Sierra Hybrid can accelerate up to 30 mph on electric power alone, after which the engine is automatically re-started. At highway speeds, the Active Fuel Management cuts out four of the engine's eight cylinders to save fuel. The batteries are recharged during deceleration and braking; there is no plug-in charging.

Actual EPA fuel-economy figures have not yet been determined, but GMC claims the combination of the 2-Mode Hybrid system and Active Fuel Management provides a 40-percent increase in city fuel economy and a 25-percent improvement in overall fuel economy. Other benefits of the system include an electrically driven air-conditioning compressor (rather than engine-driven) that allows the a/c to be running even when the engine is not.

Rear-drive versions of the Sierra Hybrid carry a maximum payload rating of 1459 lbs and a towing capacity of 6100 lbs. With 4WD, the figures are 1418 and 5900, respectively.

Sierra Hybrid is due to go on sale in the fourth quarter of 2008 as a 2009 model. Prices have not yet been announced.

GMC Denali XT Hybrid Concept

2008 Chicago Auto Show
GMC Denali XT Hybrid Concept

2008 Chicago Auto Show
GMC Denali XT Hybrid Concept

Hybrid vehicles are all the rage these days, and General Motors certainly has its share. But the GMC Denali XT Hybrid concept offers a lot more than just better fuel economy.

Unlike other pickups in the GM stable, the XT is built on a car-type unibody platform that is lighter than a conventional body-on-frame design. It's also fitted with control-enhancing independent rear suspension and height-adjustable suspension. Unusual for a show truck, it's rear-wheel drive rather than 4-wheel drive.

The XT's chop-top crew-cab body flows into an integral 4.5-ft cargo bed. Like Chevrolet's Avalanche, the XT features a drop-down "midgate" that separates the bed from the passenger compartment. When folded down, it allows longer loads to be carried. Unlike Avalanche, however, the rear window is stationary--an aid to structural rigidity, says GMC.

In wheelbase and overall length, the XT is about the same size as GMC's compact Canyon crew-cab pickup. However, at nearly ten inches wider and a couple of inches lower, it appears to hunker down over its massive 23-inch wheels.

The XT is billed as GM's first use of an E85-capable engine in a hybrid application. It's powered by a 4.9-liter version of GM's venerable "small-block" V8 featuring direct-injection technology along with Active Fuel Management, which cuts out four of the eight cylinders under light cruise conditions to save fuel. It's mated to the same 2-Mode Hybrid system used in other GM trucks. The system allows the engine to shut down when the vehicle is stopped, and it uses an electric motor powered by a 300-volt nickel-metal-hybrid battery that can propel the truck up to 30 mph before restarting the engine. GM claims the combination delivers a 50-percent increase in overall fuel economy compared to similar-size compact pickups. GMC also notes that the XT's "robust design form" hints at future styling trends for the brand.

2008 Chicago Auto Show