The X4 will share its platform and underpinnings with the second-generation X3 (pictured above), and powertrains are rumored to be the same, as well. The X3 is currently offered with BMW's 2.0-liter turbocharged inline-four and larger 3.0-liter turbocharged inline-six.
To differentiate the X4 from the X3, it will utilize completely different styling and packaging. The front end will be more aggressive and pronounced, and the roofline will have a more rakish (read: coupe-like) slope. Think of the X4/X3 relationship as a smaller version of what BMW has done with the X6/ X5.
But, as if the X4 niche itself weren't narrow enough, Autoweek states that BMW will also be bringing a higher-performance X4 M to market, despite the fact that there has never been a production X3 M. The X4 M will likely use a specially tuned version of the new turbocharged six-cylinder engine that's expected to debut in the next M3. A diesel version of the X4 M – using the 3.0-liter tri-turbo six found in other European M cars – is also reportedly in the works, though it won't likely be offered in North America. BMW will build the X4 alongside the X3 CUV at its facility in Spartanburg, South Carolina.