The X4 is what BMW calls a Sport Activity Vehicle, i.e. a compact luxury SUV combining the stylish exterior and handling of mid-size sports sedan with the high seating position and versatile interior of an SUV. Powered by a choice of strong and rather frugal turbocharged four- and six-cylinder engines driving all wheels through an 8-speed automatic transmission, the X4 builds on a rigid chassis that allows for a sporty, yet comfortable suspension setup. Inside, the X4 offers seating for five and benefits from high-quality materials, but suffers from reduced back-seat and trunk space as a result of its tapering roofline.