The feature is expected to improve the fuel economy of the base Impala with the 2.5-liter EcoTec four-cylinder engine by nearly 5 percent. Nearly 30 percent of retail buyers choose the base engine. The 3.6-liter V-6 engine option will not include stop-start technology.
The 2.5-liter Impala gets an EPA-estimated fuel economy of 22 miles per gallon city, 31 mpg highway, and 25 mpg combined.
GM added stop-start technology to its 2014 Malibu mid-size sedan that improved fuel economy by 14 percent. The technology automatically shuts down the engine, while the vehicle is stopped, and restarts it when the driver takes removes their foot from the brake pedal.
The 2015 Impala goes on sale this summer with a starting price of $27,735 for the four-cylinder LS model and $30,960 for the six-cylinder LT model. The prices include a $825 destination charge.