Stop-start standard in four-cylinder 2015 Chevrolet Impala

But Chevy Discontinuing More Efficient Mild-Hybrid eAssist Model

Chevrolet has announced that it will include stop-start technology as standard in the entry level 2015 Impala. The result is a nearly five-percent improvement in city fuel economy, also known as one mile per gallon, up to 25 mpg, combined.

The 3.6-liter V-6 Impala will not feature stop-start.

The 2015 Impala comes equipped with Chevrolet's 2.5-liter Ecotec four-cylinder engine, which will also offer 22 mpg in the city, and 31 on the highway. The 3.6-liter V-6 Impala will not feature stop-start and the mild-hybrid eAssist model from the 2014 MY, which got 29/25/35 combined/city/highway mpg, has been discontinued. Chevrolet spokesman Chad Lyons told Green Car Reports that not even one percent of the 2014 Impalas purchased were the Eco model.

So Chevy is trying something different. With a seamless driving experience in mind, the new Impala's stop-start tech features software that governs under what conditions the feature will activate. The engine won't shut off if the car has not reached a speed of six miles per hour, so the start-stop won't be cycling during traffic jams. It can also fire the starter even if the engine has not come to a full stop, which quickens reaction time, particularly in instances of what Chevrolet calls "change-of-mind events." The stop-start function uses information about cabin temperature and humidity as well as battery charge to help determine whether or not to shut off the engine.

The 2015 Impala has been engineered to reduce NVH, which will also help create a smoother stop-start experience for occupants, Chevy says. Motor mounts have been updated, and a burlier starter motor will help restart the engine after a stop.

The Impala follows the 2014 Malibu as Chevrolet's second vehicle to feature stop-start tech. The four-cylinder model currently makes up over 30 percent of Impala sales. The 2015 Impala will be available beginning this summer, with a base MSRP of $27,735 (including destination charges). And while one MPG isn't a huge difference, neither is the price increase of just $50 for a bit of eco-minded innovation. Read on for more details in the press release below.
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Chevrolet Makes Stop/Start Standard in 2015 Impala

Technology improves city fuel economy by 5 percent


DETROIT – Stop/start technology will be standard on the 2015 Impala base 2.5-liter ECOTEC® engine, an addition that improves the vehicle's city fuel economy by nearly 5 percent, or one mile per gallon.

The Impala comes standard with a four-cylinder engine, which currently accounts for more than 30 percent of Impala retail sales. It offers customers higher mpg city ratings and a more affordable entry price into the segment than six-cylinder competitors.

Stop/start shuts down the engine in certain driving conditions to reduce fuel consumption. The technology is becoming more prevalent worldwide. A recent report from Navigant Research predicted worldwide sales of vehicles with stop/start technology will grow from 8.8 million in 2013 to 55.4 million in 2022.

The 2.5L Impala with stop/start yields an EPA-estimated fuel economy of 22 mpg city, 31 for the highway and 25 combined. The Impala with the 3.6L V-6 engine will not include stop/start technology.

The Impala becomes the second vehicle in Chevrolet's U.S. lineup to feature stop/start technology, following the segment-first standard inclusion in the 2014 Malibu introduced late last year. The technology helps improve the Malibu's city fuel economy by 14 percent.

Chevrolet engineers developed the stop/start in the Impala from extensive experience with GM's eAssist system and the accompanying algorithms that allow engines to engage and disengage subtly.

"Stop/start system customer research indicates they want the engine to start up as quickly and smoothly as possible after a stop," said Mark Meyers, Chevrolet Global Vehicle Performance manager.

During the development of this technology, a team of software engineers was created. The Center for Excellence focuses on advancing stop/start technology and making its operation seamless to the customer.

A big challenge for the team was overcoming "change-of-mind events," instances in which the driver begins to stop, but then quickly accelerates. The algorithms adapt the system so the starter can fire even if the engine did not fully shut off.

The smart software also prevents the system from engaging if the car does not reach 6 mph since its last start, a welcome feature in stop-and-go-driving conditions. The system also considers cabin temperature, humidity, battery charge and other factors when deciding if the engine should come to a stop.

Hardware revisions also have been made. The noise and vibration team worked closely with drivetrain engineers to revise motor mounts to provide the greatest isolation possible from the cabin. Additionally, the team included a larger heavy-duty starter motor to assist with the additional ignition cycles.

The 2015 Impala goes on sale this summer with a suggested starting price of $27,735 for the 4-cylinder LS model, and $30,960 for the 6-cylinder LT model. These include an $825 destination charge, but exclude tax, title, license and dealer fees.

For the 2015 model year, the Impala will be available with two powertrains, a standard 2.5L engine with stop/start, and a premium 3.6L six-cylinder engine.

Chevrolet Impala Information

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