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%, or one mile per gallon. The Impala comes standard with a four-cylinder engine, which currently accounts for more than 30% of Impala retail sales.
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. The Impala with the 3.6L V-6 engine will not include stop/start technology.
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 (SSVs) 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 (10.7 l/100 km), 31 mpg (7.6 l/100 km) for the highway and 25 mpg (9.4 l/100 km) combined.
The Impala becomes the second vehicle in Chevrolet’s US. 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%.
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.—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 software also prevents the system from engaging if the car does not reach 6 mph (10 km/h) since its last start—a feature for 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.
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