Car sales are rising in many parts of the world. It seems that wherever you are, as soon as people have got a bit of cash the first thing they want to buy is a car. The industry-leading Detroit motor show has launched new models amid a wave of optimism from the US car makers. But will the popularity of the personal [bad word] to an end if the driverless vehicle [bad word] a reality? Justin Rowlatt and guests look at the future of the global car industry.