|Chassis and powertrain of the Vue Green Line 2 Mode hybrid. Click to enlarge.|
GM will unveil the 2009 Saturn Vue Green Line 2 Mode, the first front-wheel-drive compact SUV powered by GM’s two-mode hybrid technology at the North American International Auto Show, running in Detroit from 13-27 January.
GM anticipates the Vue Green Line 2 Mode will deliver an estimated 50% fuel economy increase over the non-hybrid V-6 Vue. It also is expected to have a driving range of more than 500 miles (800 km). Production is slated to begin in late 2008.
The Vue Green Line 2 Mode will qualify as a Partial Zero Emissions Vehicle (PZEV) in the state of California and other states that have adopted California’s motor vehicle emissions rules.
The Vue Green Line 2 Mode is GM’s first application of two-mode technology on a front-wheel-drive vehicle. The two-mode system is currently on the V-8-equipped Chevrolet Tahoe 2 Mode and GMC Yukon 2 Mode full-size SUVs, and becomes available in 2008 on the Cadillac Escalade 2 Mode luxury SUV and Chevrolet Silverado 2 Mode full-size pickup.
The two-mode system consists of twin, active-cooled 55-kW electric motors integrated into the 2MT70 automatic transmission. Energy to power the motors comes from a 1.8 kWh, 300V nickel-metal hydride battery pack, which consists of 22 nickel-metal hydride modules and is packaged behind the second-row seat below the cargo floor.
The transmission is mated to GM’s 3.6L V-6 VVT with direct injection technology. In the first mode, at low speed and light load, the Vue Green Line 2 Mode operates in one of three ways depending on conditions and battery charge level: all-electric power, internal combustion engine power or a combination of the two. All reverse operation is driven by the electric motors.
The second mode is used primarily at highway speeds to optimize fuel economy. It provides electric assist in addition to six-cylinder power when conditions demand it, such as trailer towing and climbing steep grades, and to allow the engine to run at its most efficient point under less-demanding conditions.
No engine speed changes are necessary for the mode shift to occur. The result is exceptionally smooth, seamless acceleration and responsiveness. At all times, the system’s Hybrid Optimizing System (HOS) collects torque-based data, deciphers it, then determines the most fuel-efficient means of propelling the Vue Green Line 2 Mode.
The Vue Green Line 2 Mode’s standard engine is an advanced 3.6L V-6 VVT with direct injection, a member of GM’s family of high-feature V-6s. The direct injection engine uses regular unleaded fuel.
Direct injection delivers fuel directly to the combustion chambers and permits a higher compression ratio (11.3:1), improving fuel efficiency. Additionally, the technology reduces cold-start hydrocarbon emissions by up to 25%.
The 3.6L VVT with direct injection also features a US auto industry-first isolated fuel injector that greatly reduces the ticking noise associated with other direct injection engines. Other noise-reduction features include the use of acoustic foam in the engine valley and cover.
Because the hybrid system changes the weight distribution on the Vue Green Line 2 Mode, special chassis refinements such as revised front and rear spring rates; revised front and rear stabilizer bar rates and recalibrated front struts and rear shock absorbers help ensure a smooth driving experience.
The Vue Green Line 2 Mode is equipped with a “fully blended” electro-hydraulic brake system that enables 100% regenerative braking (batteries are charged during braking), 100% friction braking (traditional four-wheel disc braking) or a combination of the two. During regenerative braking, the system converts kinetic energy to electrical power, then stores the power in the Energy Storage System.
A 12V rack-mounted Electric Power Steering system replaces a conventional column-mounted hydraulic system and saves fuel, gaining up to a half-mile per gallon of gasoline.
When it arrives in dealer showrooms in the fourth quarter of 2008, the Vue Green Line 2 Mode will be Saturn’s third hybrid, joining the Vue Green Line 4-cylinder hybrid SUV and the Aura Green Line sedan.
GM is also working on a plug-in version of the Green Line 2 Mode. GM has awarded advanced battery development contracts to the A123Systems-Cobasys partnership and Johnson Controls–Saft Advanced Power Solutions, LLC to design and test lithium-ion batteries for use in the PHEV version. (Earlier post.)