BRDC president Damon Hill has estimated Silverstone's chances of retaining the British grand prix beyond 2009 at just "50-50".
F1 chief executive Bernie Ecclestone is demanding higher race fees and substantial improvements to the circuit in Northamptonshire.
"I would say 50-50 is probably about right," Hill, also 1996 world champion, told British reporters at the Silverstone test on Thursday.
"It's one step at a time; the negotiations typically will be ongoing and I expect won't come to a conclusion until the final hour, whenever that is."
The track's owner, the British Racing Drivers' Club, has devised plans for new facilities at Silverstone, but money is still the key hurdle.
One ingredient in Silverstone's favour, however, is Lewis Hamilton, whose popularity must be credited for a sell-out crowd for next weekend's British grand prix.
10,000 attended the circuit on Thursday, to watch the McLaren driver simply top the test times.
"(He is) very important," Hill acknowledged. "But I would not presume that because we have got Lewis Hamilton contending for the world championship, that guarantees the future of the grand prix."
Another factor on Britain's side is the apparent FIA protection - part of the contracts between the governing body and F1's owners - for the British GP and other 'traditional' races on the calendar.
But unlike some of the British media, Hill does not scoff at reports that Donington is a possibility to host the British grand prix from 2010, although admitting that the government is unlikely to come to Silverstone's rescue.
The 47-year-old, though, didn't want to wade too far into the murky politics between Ecclestone and the FIA's Max Mosley at present.
"We would like to avoid the taking of sides on that one. But if there was a way of it becoming a protected event, that would be of interest - but we are certainly not relying on that," Hill said.
F1 chief executive Bernie Ecclestone is demanding higher race fees and substantial improvements to the circuit in Northamptonshire.
"I would say 50-50 is probably about right," Hill, also 1996 world champion, told British reporters at the Silverstone test on Thursday.
"It's one step at a time; the negotiations typically will be ongoing and I expect won't come to a conclusion until the final hour, whenever that is."
The track's owner, the British Racing Drivers' Club, has devised plans for new facilities at Silverstone, but money is still the key hurdle.
One ingredient in Silverstone's favour, however, is Lewis Hamilton, whose popularity must be credited for a sell-out crowd for next weekend's British grand prix.
10,000 attended the circuit on Thursday, to watch the McLaren driver simply top the test times.
"(He is) very important," Hill acknowledged. "But I would not presume that because we have got Lewis Hamilton contending for the world championship, that guarantees the future of the grand prix."
Another factor on Britain's side is the apparent FIA protection - part of the contracts between the governing body and F1's owners - for the British GP and other 'traditional' races on the calendar.
But unlike some of the British media, Hill does not scoff at reports that Donington is a possibility to host the British grand prix from 2010, although admitting that the government is unlikely to come to Silverstone's rescue.
The 47-year-old, though, didn't want to wade too far into the murky politics between Ecclestone and the FIA's Max Mosley at present.
"We would like to avoid the taking of sides on that one. But if there was a way of it becoming a protected event, that would be of interest - but we are certainly not relying on that," Hill said.