Official EPA numbers underscore the progress Buick has made on gas mileage.
The LaCrosse comes in two models, one specifically geared toward higher fuel economy, the other with more ample luxury-minded performance. For 2014, the eAssist mild-hybrid powertrain delivers an EPA-rated 25 mpg city, 36 mpg highway, for a combined gas mileage figure of 29 mpg. That's a very good number for a large sedan, and in real-world driving, our editors have seen about 30 mpg in 270 miles of mixed driving.
A word of caution, though. While we've been able to come close to replicating the LaCrosse's 36-mpg highway rating, we've found it challenging—virtually impossible—to see the EPA test's 25 mpg in city driving. The trip computer's figures in typical city driving have been more in the 19 to 21 mpg range.
With the available V-6 engine, the LaCrosse's fuel economy is less impressive. Its EPA figures come in at either 17/26 mpg or 20 mpg combined for the all-wheel-drive version, or 18/28/21 mpg for the front-drive V-6 car.