VOLVO Car Corp. (VCC) this month has started equipping a start/stop system to its cars with automatic gearboxes, according to Volvo Phils. The start/stop system, which was initially offered only with the company’s 2.0-liter D3 turbo diesel engine, is now available for the D3 versions of the Volvo S60, V60, V70 and S80 that have six-speed automatic transmissions.

Volvo said the technology cuts CO2 emission by 10 grams per kilometer and reduces fuel consumption by 0.4 liters for every 100 kilometers.

“Continuously reducing CO2 emissions from conventional power trains is an important part of our DRIVe Towards Zero emissions program, said VCC Senior Vice President for Research and Development Peter Mertens. “It is the most effective way to cut CO2 throughout our model range in the short term. This work is running parallel with our innovative focus on electrification technologies.”

VCC said that combining the start/stop system with an automatic gearbox is a larger challenge than if it’s paired with a manual because the engine must restart instantly when the driver steps off the brake pedal and onto the accelerator. The system uses brake pressure measurement to trigger when to stop and start the engine, and is programmed to shut down the engine immediately when the car reaches a standstill. An electric pump keeps oil pressure up in the automatic gearbox while the engine is stopped.

“We have focused on achieving the same agile feeling as you get with today’s conventional automatic,” Mertens said. “The response is so seamless that it feels like the car starts accelerating immediately when the engine restarts.”

VCC reckoned the start/stop system has allowed for the S60 to achieve a fuel consumption of 5.4 liters per 100 kilometers, the V60 and V70 of 5.7 liters per 100 kilometers and the S80 of 5.6 liters for the same distance. In terms of emission, the S60 is rated at 142 grams per kilometer, the V60 and V70 at 149 grams per kilometer and the S80 at 148 grams per kilometer.