The 2013 Buick LaCrosse is merely average among larger sedans if you get the available V-6 engine. As such, its EPA figures come in at either 16 or 17 mpg in the city, and 26 or 27 on the highway.
It's a completely different story with the base eAssist powertrain, though; incorporating a new version of GM's mild-hybrid belt-alternator-starter system, these models are mileage standouts, with ratings of 25 mpg city, 36 mpg highway, for a combined gas mileage figure of 29 mpg.
Especially for those who log a lot of highway miles, the 2013 Buick LaCrosse is one of the greener large-sedan picks.
In real-world driving, we've seen about 30 mpg in 270 miles of mixed driving with one editor, and about 23 mpg in 160 miles of mixed driving with another editor (somewhat less highway driving). A cautionary note for those with urban commutes: Though 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.