The 2015 Chevy Impala is losing its top mileage-getter for the new model year, while it's also adding stop/start to the base four-cylinder. In the end, the mileage weighting of the lineup goes down a little bit.
The former Impala Eco was fitted with GM's mild-hybrid eAssist system, and wore special aero add-ons--dams, spats, and active grille shutters that smooth the nose for better efficiency--to gain a 29-mpg combined figure.
With it gone, the stop/start four-cylinder is the efficiency leader (the six-cylinder won't be getting the technology).The EPA hasn't published the Impala's final gas-mileage ratings, but Chevy estimates the base vehicle will come in at 25 mpg combined (22 mpg city, 31 mpg highway).
Last year the more powerful V-6 checked in at 21 mpg combined (18 mpg city, 28 mpg highway). The combined rating for the V-6 falls below the Toyota Avalon's 25 mpg, the V-6 Taurus' 23 mpg combined, and the 23-mpg figure posted by the Hyundai Azera and the Dodge Charger with its eight-speed automatic.
In our first-drive test loop set up by Chevy, the V-6 Impala's indicated economy checked in at 20.3 mpg, tallied after lots of canyon runs and a few stretches of 75-mph interstate.
We logged 25.1 mpg--right on the nose--for the base 2.5-liter four-cylinder Impala, albeit over a short 20-minute drive covering about 12 miles.
We'll update this section when EPA data is published.