Is a visa required to leave Guangzhou airport/transit for a eight hour sightseeing bus tour?

Hi, I am travelling from India to NZ in June via a sixteen hour transit in Guangzhou. It would like to do an eight hours sightseeing bus tour of Guangzhou rather than spending sixteen hours waiting in the airport. Do I need a visa for China to do the tour? Is my onward ticket sufficient to go out of the airport for the tour?