High Quality Content by WIKIPEDIA articles! The BMW X3 is a compact crossover SUV marketed by the German automaker BMW, based on the BMW 3-Series automobile platform, and now in its second generation. BMW designed the X3 in conjunction with Magna Steyr of Graz, Austria — who manufactured all X3s under contract to BMW for the first generation. Production of the second generation vehicle has transferred to BMW`s Spartanburg plant in South Carolina, USA.