The driver in a car crash that killed Nelson Mandela's great-granddaughter has been acquitted by a South African court, his lawyer has said.Sizwe Mankazana was cleared of all counts, including driving under the influence of alcohol, the lawyer said.He was driving 13-year-old Zenani Mandela home from a concert in Soweto to kick off the 2010 football World Cup when the car hit a steel barrier.Zenani was one of Mr Mandela's nine great-grandchildren.The anti-apartheid fighter, who became South Africa's first black president, had campaigned for the World Cup to be held in South Africa.Mr Mankazana's lawyer, Hulme Scholes, said the magistrate had described the crash as a "freak accident", the South African Press Association (Sapa) news agency reports.Mr Mankazana had been acquitted of reckless driving, driving under the influence of alcohol and culpable homicide, he said.Zenani's grandmother Zindzi is now spear heading a United Nations campaign for road safety, the AP news agency reports.South Africa has one of the world's worst road safety records, and there is an average of 42 deaths each day on roads across the country, correspondents say.