Friday, August 6, 2010

GM Plots Return to Mild Hybrids

Saturn Vue

The Saturn Vue mild hybrid relied on first-generation mild hybrid technology that shuts off the engine when not needed and provides power assistance during rapid acceleration. G.M. says the newest version of that system will be vastly improved in both performance and fuel economy.

Less than a year after pulling its mild hybrids off the market, General Motors announced that it will bring back the less expensive hybrid technology. According to Larry Nitz, G.M.'s executive director of hybrid and electric powertrain engineering, the carmaker is prepared to roll out the next generation of its mild hybrid technology on at least one mid-sized sedan next year. The new powertrain reportedly will be equipped with a lithium ion battery supplied by Hitachi, and will provide about four times as much power and will be 24 percent smaller and 40 percent lighter than previous mild hybrid battery packs.

Unlike a full hybrid system, a mild hybrid system cannot propel a vehicle on electric power alone. It only shuts off the gasoline engine when the car stops and then uses the batteries to restart the engine. The electric motor also provides a boost during acceleration.

When the Saturn Aura won "Car of the Year" at the 2007 North American Auto Show, and that model had a mild hybrid variant, it looked like G.M. might be getting ready to launch hybrids into its mainstream lineup. G.M. would eventually offer five mild hybrid vehicles: the Aura; the Saturn Vue Green Line; the Chevy Malibu hybrid; the Chevy Silverado hybrid; and the Buick Lacrosse EcoHybrid, which was sold only in China. But across all five models, the GM never produced more than about 15,000 vehicles per year and by summer of 2009, all had been canceled. (Beginning in 2009, Chevy switched the Silverado hybrid to a full-hybrid, its so-called "two-mode" hybrid system.)

Starting and Stopping

In June 2009, G.M. cited low sales as the reason for cutting the Malibu Hybrid.

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