The higher-performance hunchback follows in the footsteps of BMW's other sub-M cars like the M235i. In fact, much like the high-po 2 Series, the M40i is expected to make use of a 3.0-liter, turbocharged six-cylinder, developing 365 to 375 horsepower.
Aside from that, the rest of the X4 M40i fits the brief of other near-M models, with a more aggressive body kit, larger wheels, firmer suspension and brawnier brakes. Expect some mild tweaks inside, too, including sportier seats and an M-specific steering wheel.
Judging by the uncamouflaged nature of this tester caught testing on Germany's Nürburgring, production will kick off before the end of the year, perhaps in December. That means a LA Auto Show debut is likely, provided BMW opts to sell the hotter X4 in the US market. Take a look above for our full gallery of spy photos.