Mr Zulu was part of 40 South Africans who were part of a Nelson Mandela-linked charity raising funds to buy sanitary towels for girls.
Mr Zulu and his wife Letshego both descended Mount Kilimanjaro when he experienced breathing problems on Sunday, according to local reports.
In his last Facebook post, the driver posted he had flu-like symptoms.
Mr Zulu won the hearts of many South Africans with his warm spirit as a motorsport television presenter and was well-loved even by those who did not follow racing, say the BBC’s Pumza Fihlani in Johannesburg.
“Made it though (stet) day2. My wife is doing fabulous, she has even learnt the local language. Am having flu like symptoms and struggling with the mountain but taking it step by step!! Today we managed to see our destination and our camp is literary above the clouds!!” he said in his last post 16 July.
The pair, affectionately known as the “adventure couple”, were celebrated in South African sporting circles.
‘I am devastated’
Messages of condolences have poured in from across the country, with many posting wishes for his widow and their one-year-old daughter Lelethu.
The celebrity couple were taking part in the Trek4Mandela Caring For Girls, an expedition led by the Nelson Mandela Foundation aimed at raising funds for underprivileged communities to ensure girls would not miss a day from school due to menstruation.
“I am devastated. I knew him well. I recruited him to climb Kilimanjaro. The last thing he said to me at the airport before he left last week was that he wanted to speak about doing other Mandela Day projects. I feel a huge sense of loss,” said the foundation’s CEO Sello Hatang.
The group had planned to climb Kilimanjaro to mark Mandela Day, a United Nations recognised day which falls on the late statesmen’s birthday – 18 July.
It encourages people all over the world to do community service in honour of the first democratically elected president of South Africa.