The tablet, called the MPG Cap, is added to fuel tanks to make fuel burn more efficiently, said Tim Dunstan-Smith, who claims he was the first person to bring the product to South Africa.
"The product is two-pronged. It saves between seven and 14% fuel in a combustion engine and it reduces 75% of harmful emissions into the environment," he told Sapa.
Dunstan-Smith launched the tablet in South Africa last October but recent press coverage has seen public interest in the product increase.
"It's growing every day, it's really starting to snowball," he said, adding: "We are getting a lot of interest from trucking companies."
The tablet costs about R25 - depending on the rand dollar exchange rate - and an 80-litre full tank needs one pill.
This equated to an average saving of R60 per full tank, after the costs of the pill is deducted, he said.
The tablets are for sale directly from distributors.
Dunstan-Smith said there were currently about 300 distributors in South Africa and the tablet was available in more than 200 countries world-wide.
It was first launched by a company called Fuel Freedom International (FFI) in the United States in 2005.
The tablet was safe to use in car engines and FFI had public liability insurance worth $2m to cover engine damage - but there had been no claims so far, said Dunstan-Smith.
The Star newspaper reported on Monday that NBC journalists, who described themselves as "big time sceptics", tested the product in 2006 with "astonishing results".
Automobile Association spokesman Gary Ronald said he had not heard of the MPG Cap but said consumers should be careful.
"We are very sceptical about fuel-saving gadgets. Some of them do appear to save fuel but the savings are marginal, considering the cost of the gadget," said Ronald.