Justin Rowlatt and Anita Rani explore how safe the roads and cars of Britain are and what can be done to cut casualties. Most accidents are caused by human error but what kinds of errors are the biggest killers on the roads? Anita Rani and Justin Rowlatt consider the dangers of mobile phones, how do they compare to alcohol consumption or lack of sleep? And are some people more prone to accidents than others? Research suggests men and women crash in different ways, likewise the young and the old. Justin and Anita get the scientists out of the lab to carry out tests on the Great British public. They use what they find out to examine current proposals: should we re-test the elderly or ban the young from driving with friends? The programme explores what's behind the statistics through access to unique video collection of drivers caught on camera during accidents and near misses, showing the errors as they happen - including Justin and Anita's own.