MUNICH, Germany – BMW has a history of carving unexplored niches. The first X-badged model, the X5 launched in 1999, saw the introduction of what the German automaker called the Sports Activity Vehicle (SAV). The hugely popular X5 paved the way for the automaker’s X3 and X1. In May 2008 BMW chipped another niche with the introduction of the BMW X6, touted as the first Sports Activity Coupé. There's lots in a name...Image gallerySince the introduction of the first BMW X unit average sales across the automaker’s line-up have soared - one in four new BMW's globally is an X model.ASSERTIVE CROSSOVER DESIGNIn 2013, BMW reveals the next addition to its X family – the concept X4. The X4 will build on the automaker’s X6 SAC and create "a new vehicle class" (the SACV? CSAC? SAUCV?).The concept will make its debut at the 2013 Shanghai auto show in April, with the model set to be launched in 2014. It will be built at the automaker’s Plant Spartanburg in the USA, which produces the X5, X6 and X3.Though the new model borrows design cues from the X6 it will ride on the same platform as the X3. The X4 is 4.6m long, 1.9m wide, 1.6m tall and a has a 2.8m wheelbase; that's 22.6cm shorter and 7.1cm lower and wider than the X6.When it reaches production, the X4 will be sold with a choice of four and six-cylinder petrol and diesel engines each mated to an eight-speed auto and BMW’s all-wheel drive system.In design terms, it looks like a compact X6 and sports a larger version of BMW’s kidney grille flanked by a pairs of LED's. The concept has 21” alloy rims and LEDs at the rear. The X4’s rear combines the curves of a coupe with that of a practical hatchback SUV.The X4 is intended to be a sleeker, more stylish and sophisticated, version of the X3 despite looking like a more compact X6.