BMW's adopted a new eight-speed automatic transmission in the X5, but fuel economy climbs only by a mile per gallon here and there.
The xDrive35d diesel is EPA-rated at an impressive 24/31 mpg, or 27 mpg combined. The V-8-powered xDrive50i model doesn't move forward as briskly in gas mileage. It's rated at 15 mpg city and 22 mpg highway for 17 mpg combined.
As of last year, the X5 xDrive35i steps up its game from 16 mpg city, 23 mpg highway to 18/27 mpg, or 21 mpg combined.
Figures for the X5 M are 14/19 mpg or 16 mpg combined