The X3 premiered in September 2003 at the Frankfurt Auto Show (Internationale Automobil-Ausstellung), sharing its rear suspension with the E46 330xi and using an automatic four-wheel drive system marketed as "xDrive." All X3 models feature BMW's all-wheel drive system, with a default 40:60 torque split between the front and rear axles and the ability to direct all torque to either axle. The system used an electronically controlled multiple-plate clutch to enable infinitely adjustable, fully variable distribution of torque from front to rear with the capability of up to 100 percent of engine torque going to either axle. BMW markets the crossover as a "Sports Activity Vehicle", the company's descriptor for its X-line of vehicles.