Jim Al-Khalili traces the history behind the invention of the car. The journey begins with the earliest known evidence of dog sleds, dating back 9,000 years to a settlement in Siberia and pulled by domesticated grey wolves. The programme moves on to the invention of the wheel - and the bronze tools that made its creation possible - and the tragic story of Carl Benz, who invented a motor car but failed to sell any. Finally, there is a look at modern solutions to the pollution caused by motor vehicles