GM Mild Hybrid Cutaway

Cutaway of the previous version of G.M.’s mild hybrid technology, briefly put to use on discontinued Saturn and Chevy hybrids.

Earlier this month, we reported that General Motors will bring back its low-cost mild hybrid technology. G.M. will start with at least one mid-sized mild hybrid sedan next year—ramping up to 100,000 mild hybrids per year. Does this mean that G.M. is slowing down on production of the Chevy Volt, or wavering from global plans for more electric cars? No. But everyday we see more evidence that the entire auto industry’s green car roadmap begins with more efficient gas engines, then conventional hybrids, and finally plug-in cars.

“After we’ve explored everything in a conventional system, the next logical step is in mild hybrids, then strong hybrids and electrics,” said Larry Nitz, engineering director for hybrid electric powertrain engineering for GM global product operations. Nitz, speaking at the Center for Automotive Research’s Management Briefing Seminars in early August, was quoted by Plastics News.

That roadmap bears a striking resemblance to Ford’s electrification strategy. Ford puts “Ecoboost,” its fuel-efficient conventional internal combustion technology, as the first milestone on its green trajectory. Ford’s Nancy Gioia, director of vehicle electrification, says that hybrids and electric cars could make up 25 percent of the company’s offerings by 2020. But she always qualifies the claim by saying that 75 percent of those vehicles will be conventional hybrids, and only a small percentage points for full battery-electric cars. Ford’s conventional gas-electric cars are full hybrids.

G.M.’s new mild hybrid 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.

So while the Chevy Volt, Nissan LEAF and other electric cars take center stage in the coming months, auto engineers’ first priority is making gas-powered vehicles go further on a gallon of gas. That’s true for Ford, as well as GM which expects that conventional gasoline engines will still be on 80 percent of all vehicles in 2020. And it’s even true for Nissan, which sees electric cars rising to 10 percent of its sales by 2020. The other 90 percent will have a gas engine on board—many of them assisted by batteries and an electric motor.