GM to Unveil Upgrade
Of Its Hybrid Powertrain
March 3, 2008 4:00 p.m.

GENEVA -- General Motors Corp. Vice Chairman Bob Lutz said his company's new hybrid system will be able to drive on electric power alone at very low speeds.

The new powertrain, which GM plans to unveil Tuesday at the Geneva Motor Show, is an upgrade of the auto maker's current "Belt Alternator Starter," or BAS, drivetrain that is used on hybrids such as the Saturn Aura and Chevrolet Malibu.

The system is a so-called "mild" powertrain, which gets limited fuel savings because it doesn't generally drive on electric power alone. That's in contrast to the more efficient "full" system in Toyota Motor Corp.'s Prius car.

GM will upgrade its system with more powerful lithium-ion batteries. GM will call the new system "BAS-plus," according to people familiar with the company's plans. The first supply contract for the batteries will go to Japan's Hitachi Ltd., these people said.

Mr. Lutz, speaking at the Parc Des Eaux-Vives hotel, said the upgrade to lithium-ion batteries will allow the new hybrid system to produce "limited electric drive" during the "extremely fuel-consumptive phase of initial acceleration." He said the lithium-ion battery would provide a charge of 120 volts, compared to the 30-some volts GM currently gets from nickel-metal hydride batteries.

While Mr. Lutz conceded the system won't get the 30% to 35% mileage boost that other hybrid systems get, he said it would be better than the 12% to 15% benefit in GM's current BAS system.

Mr. Lutz also stressed that the system is less expensive than other electric-only driving hybrid systems and therefore more cost-effective for consumers.

Many full hybrids cost thousands of dollars more than comparable gas-engine models. Mr. Lutz said full hybrids only make sense today in large vehicles such as GM's two-mode hybrid sport-utility vehicles, where the vehicle is already expensive.