Plot: Olympic swimmer and Strictly Come Dancing contestant Mark Foster tests a supercharged Vauxhall VXR8, Jonny Smith watches classic vehicles being raced at the Firecracker Banger meet, and Tim Shaw retakes his driving test in a Nissan Micra. Plus, Vicki Butler-Henderson assesses the Smart MHD city car, Jason Plato compares two Renaults, and Tiff Needell examines the new Porsche 911