On Friday Porsche published a first teaser image of the all-new third-generation Cayenne, which is set for launch on August 29. And though the picture is sketchy, it shows that -- true to the company's form -- the next car will be an evolution of its predecessor, in terms of exterior design. But, Porsche being Porsche, there will be a huge revolutionary leap in performance. Indeed, most commentators expect the range-topping model to feature a hybrid ...