Caterham and Marussia are likely not debuting a new car for 2015.
Caterham and Marussia are nearing the end of the line as other teams move preparations for the 2015 season into high gear.
With just 26 days until the winter test season begins in Spain, neither of the beleaguered backmarkers are committing to running at Jerez at the start of February.
"Talks with interested parties continue," Caterham administrator Henry Shinners told the BBC, "but if a buyer is not found before the test, we will not put up the money to go."
The team has arranged to be allowed to run its 2014 car and engine this year, but Shinners warned that any rescue deal would need to be in place within a "few weeks".
Chances of saving the team
"I wouldn't rule anything out," he said, "but if we reach the first race in the same position, the chances of saving the team are virtually nil."
It is a similar but perhaps even more dire situation for Marussia, whose debts only grew by $45,000 in a failed bid to make the Abu Dhabi grid late last season, Forbes' Christian Sylt reported.
Not only that, crucial team equipment has been auctioned in a bid to pay back creditors, staff are laid off and even the Banbury headquarters could be sold to the new American 2016 team HaasF1.
Now called Manor, the team formerly known as Marussia's last hope is that an eleventh-hour investor might step in so that millions in official prize-money for finishing last season in ninth place can be unlocked.
"There's still a slim hope," team boss John Booth told the Yorkshire Post, "but it's getting extremely late.
"We've got two weeks to complete something by. So there's still a chance," he added. "We are talking to investors and they are positive talks."