BMW is about to expand into yet another niche with its upcoming X4 "Sport Activity Coupe," a fastback version of the X3 in the same vein as the larger X5-based X6. Though we've spotted the vehicle before, we now get a glimpse of the BMW X4′s interior, and also get to see it testing alongside its X3 platform-mate.

As expected, the X4 prototype looks very much like the X3 inside, with a recessed central screen and contoured dashboard. Most of the switchgear that's not covered up appears to be in the same place, as do the HVAC vents. Any subtle differences will likely also appear on the X3 for its 2014 mid-cycle refresh.

Seeing the X4 alongside the X3 on which it's based makes the differences in styling more apparent. Like the X6, the X4 features a dramatically raked roofline. The slope begins in the middle of the roof, and continues along the X4′s stretched D-pillar until finally curving up for a slight ducktail-like rear spoiler. The taillights are obscured by camo, but don't expect them to look much different from the concept that bowed in Shanghai earlier this year.

As we previously reported, we expect the BMW X4 to be offered with the same powertrain options as the X3, including a turbocharged 2.0-liter I-4 good for around 240 hp and BMW's ubiquitous 300-hp twin-turbo 3.0-liter I-6. An eight-speed automatic will likely be the only transmission choice, with all-wheel drive standard on all models. Look for the production 2015 BMW X4′s debut sometime next year.

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Photo Source: CarPix