|The Denali XT.|
GMC will introduce a new hybrid sport-utility truck concept—the Denali XT—at the upcoming 2008 Chicago Auto Show, 6-17 February 2008. GM will also announce the 2009 GMC Sierra Hybrid, another application of the two-mode hybrid system.
The Denali XT is based on a unibody architecture rather than body-on-frame construction and combines GM’s rear wheel drive two-mode hybrid transmission with a downsized E85-capable version of GM’s small block V-8.
The new direct-injection 4.9L V-8 engine in the Denali XT also features Active Fuel Management (cylinder deactivation), and delivers an estimated 326 hp (243 kW). This is GM’s first pairing of the rear-wheel drive two-mode hybrid transmission with a smaller-displacement version of the small-block, and also the first pairing of the transmission with an E85-capable engine.
GM estimates that the Denali XT offers a 50% increase in combined fuel economy over comparable small pickup trucks when running on gasoline.
Design and construction of the Denali XT were spearheaded by Holden Design, within the Australian arm of GM’s global design and engineering network.
In city driving, all-electric propulsion is used at low speeds; on the highway, fixed-gear operation enables efficient performance even when towing a trailer. The Denali XT has an estimated payload capacity of 1,100 pounds (499 kg) and a towing capacity of an estimated 3,500 pounds (1,587 kg).
GM says that it also used the work on the Denali XT to evolve the combination of the small-block V-8 and two-mode hybrid powertrain beyond the current production models. During this optimization process, GM says, additional powertrain technologies have been integrated, including Active Thermal Management, which transfers thermal energy from one driveline component to another to improve efficiency; and a high-efficiency axle configuration, which fundamentally reduces the losses normally associated with conventional axle configurations.
|The 2002 Terra4.|
GMC’s last hybrid concept pickup truck was the 2002 Terra4, introduced in 2001. The Terra4 provides an interesting historical contrast. Larger than the Denali XT (the Terra4 had a wheelbase of 136 inches, compared to the Denali’s 123.4 inches), the concept vehicle combined a 285 hp, 5.3-liter VORTEC V-8 gasoline engine and 4.8kW motor/generator integrated between the gasoline engine and the transmission. The Terra4 offered microhybrid functionality (start/stop, regenerative braking), and an approximate 15% increase in fuel economy.
(This was the concept debut of the start/stop hybrid system that would later briefly appear in production GM pickups in 2004.)
|The 2009 GMC Sierra Hybrid.|
The 2009 GMC Sierra Hybrid. The new 2009 GMC Sierra Hybrid, another application of the two-mode hybrid system, achieves 40% greater city fuel economy and a 25% improvement in overall fuel economy while supporting a 6,100-pound (2,767 kg) towing capacity, including in all-electric drive mode.
GM also offers a two-mode hybrid version of its Chevrolet Silverado pickup.
The two-mode hybrid system is paired with a 6.0L gasoline V-8 and 300V NiMH battery pack, and offers all-electric driving up to 30 mph (48 km/h). The engine features Active Fuel Management (AFM) and late intake valve closing (LIVC) technology. GM’s hybrid technology system not only enables the Sierra to launch and drive up to 30 mph on electricity alone, it also allows the Vortec 6.0L V-8 engine to operate in its more economical V-4 mode for longer periods.
An electrically driven 300-volt air conditioning compressor reduces vibration and allows the standard, tri-zone HVAC system to cool the passenger compartment even when the gasoline engine is shut off.
Electrically driven 42-volt variable-assist power steering reduces vibration and provides up to a 0.5-mpg fuel economy improvement by reducing parasitic losses common in belt-driven hydraulic systems.
The internal cooling fan for the Energy Storage System (ESS) is tuned to be quiet at low vehicle speeds when the fan could more easily be heard by the occupants.
The Sierra Hybrid goes on sale in the fourth quarter of 2008 and is based on the Sierra platform that was introduced for the 2007 model year. It will be offered in the Crew Cab body style on both 2WD and 4WD models.