GM plans stop-start fleetwide by 2020

DETROIT -- General Motors is going all in on stop-start.

By 2020, nearly every GM light vehicle produced globally will have at least one powertrain combination available with the fuel-saving feature, which turns off the engine when the vehicle isn't moving.

GM spokesman Tom Read said vehicles with stop-start systems will have beefed-up absorbent glass mat batteries and tandem solenoid starters. Absorbent glass mat, or AGM, batteries are sealed and have greater efficiency than normal lead-acid car batteries. AGM batteries keep the electrolyte suspended and in constant contact with the batteries' lead plates. Tandem solenoid starters enable ultrafast and smooth starts.

Stop-start systems can boost fuel economy as much as 6 percent in city or high-traffic situations. Starting in the 2017 model year, the EPA will award credits toward compliance with corporate average fuel economy standards to automakers whose vehicles have such systems, which add around $300 to a vehicle's cost.

"Everyone will end up adding start-stop," says AutoPacific analyst Dave Sullivan. "Now there's a benefit in the EPA cycle, which there wasn't a few years ago. GM's new nine- and 10-speed automatic transmissions have been engineered from the beginning to incorporate start-stop. That will make it much easier and much smoother. That's what's been the holdup. First it was a regulatory issue, then it was a hardware issue." 

The new transmissions, developed jointly with Ford, have accumulators that keep the transmission pressurized when the engine is off. That enables the vehicle to move away quickly the instant the engine is restarted. This fall, the new GM-Ford 10-speed transmission debuts in the 2017 Ford Raptor pickup and the Chevrolet Camaro ZL1. 

Tier 1 suppliers of stop-start components include Robert Bosch GmbH, Continental AG, Delphi Automotive, Denso Corp. and Valeo SA.