Over 90 per cent of road accidents are caused by human error, for instance by falling asleep, and it's an error that kills around 4,000 people every year. This Watchdog special investigates the behaviour that turns ordinary drivers into killers, and asks: "How safe is your driving?"

The programme has conducted the largest-ever survey of driving habits, and concludes that most of us are not as skilled as we think we are. When picked at random, seven out of ten experienced drivers fail the driving test!