Volkswagen AG's Porsche unveiled the Panamera coupe at the Shanghai Auto Show. The goal was to steal some show from Maserati's all-new Ghibli to win over China's growing ranks of luxury-car buyers. Other reveals: BMW AG's X4 coupe-like sport-utility vehicle, Daimler AG's Mercedes-Benz GLA compact SUV and a sedan version of the Audi A3 hatchback.