Red Bull are likely to be hit hard by technical changes banning "off-throttle blown diffusers", according to the team's chief technical officer, Adrian Newey.
From this weekend's British Grand Prix at Silverstone onwards, the practice of forcing exhaust gases over the diffuser, even when the driver is not pressing the accelerator, will be outlawed.
Newey, who designed the RB7 car around the technology, said: "We'll be quite heavily affected because our car was designed around the exhaust. Everybody else has, generally speaking, copied somebody else's principal – mainly ours – and adapted it to the car they had in pre-season.
"So it might be that because our car has been designed around it, it's going to be more of a hit for us, but it's very difficult to forecast."
Newey said he was working hard to overcome the restriction. "It is quite a bit of work because we've had to reoptimise the car around a different set of parameters to that in which it was designed and developed up to this stage," Newey said.
Officials in South Africa are treating with scepticism remarks from Formula One's chief executive, Bernie Ecclestone, that the country could host a race in two years.
Ecclestone said he is close to concluding a deal for a grand prix to be staged in Cape Town. "I think we're maybe a little bit closer than we have been for a long time," he told South Africa's Eyewitness News. However, doubts have been raised owing to the amount of money involved and the fact that the event would need government support.
Esther Henderson, chief communications officer for Cape Town Grand Prix South Africa, said: "The annual licence fee we need to pay to Formula One amounts to $40m (£25m). "We have investors that are interested, but it is a catch-22 situation because in order to give our investors security that this is happening, we need our national government's support."
South Africa last held a Formula One grand prix at Kyalami, 25 miles north of Johannesburg, in 1993