When it launches in the fall of 2013, the refreshed 2014 Chevy Malibu will be the first sedan in its class to offer a stop/start system as standard equipment in the United States. To conserve fuel, the system shuts off the 2.5 liter I4 (LCV) engine when the Malibu comes to a stop, with all electric accessories, such as air conditioning, radio, and lights, among others, continuing to work via the auxiliary battery. As soon as the driver lifts his or her foot off the brake pedal, the powerplant springs back to life.
Since learning about the system, several GM Authority readers have written in asking about the behavior of the stop/start system in the event that the auxiliary battery doesn’t have enough power to continue running the air conditioning (or other accessories), and how the system works in stop-and-go traffic. So we reached out to Chevrolet spokesman Chad Lyons for clarification, who was kind enough to provide a great explanation of the logic employed by the stop/start system. In a word, the setup as seen in the 2014 Malibu is smart, and won’t let you down. Here are the details.
By far the most common question we’ve seen thus far as it relates to the stop/start system in the ‘Bu concerns its functionality during a state of low battery charge.
As it turns out, the Malibu monitors the state of charge to determine whether or not it should shut the engine off. If the battery cannot maintain the car’s current accessory load (AC speed, other load) for at least 2 minutes, then the engine won’t be shut off. Furthermore, if the electric load increases when the car is already stopped and the engine is off, and the system determines the battery state of charge will reach its threshold, then then engine will turn back on.
To note, the auxiliary battery only powers electrical accessories momentarily during engine cranking (AutoStart).
Stop and Go Traffic
The other common question about the Malibu’s stop/start system surrounds its behavior in stop-and-go traffic.
To that end, the system is smart enough to monitor inputs like vehicle speed, the operation of the climate control system, and the force a driver applies to the brake pedal to determine whether it is efficient to shut off the engine in certain driving conditions, like during stop-and-go driving situations.
Vehicle speed is another factor that’s taken into consideration. In a situation like stop-and-go-traffic, for instance, a vehicle will usually stop, then move slowly, then stop again. The Malibu’s system monitors speed to understand that the vehicle is in stop-and-go-traffic, and that the engine should not shut off.
The result isn’t only a stop/start system that’s smart, but one that delivers 25 MPG in the city, 36 MPG on the highway, and 29 MPG combined — a rather noteworthy accomplishment since the 2.5 liter engine is one of the more powerful base engines in the U.S. midsize sedan segment.
The GM Authority Take
That’s some great stuff, Chevy! In fact, we can already see an ad for this, with the outro tagline saying, “That’s American ingenuity to Find New Roads.”
Plus, we’d love to see the technology be added to more Chevrolets, and GM vehicles in general. The Buick Regal and Cadillac ATS seem like worthy candidates.