The team was initially happy to accept that it would not run at Silverstone next week when race drivers join the test, as punishment for its secret Pirelli test earlier this year.
But AUTOSPORT has learned that Mercedes is awaiting a ruling from the FIA on whether or not there are grounds for it to get some running, so it can gather some data about the new tyres ahead of the Hungarian Grand Prix.
One of its arguments is that with Pirelli's new 2012 construction tyres being introduced on safety grounds, it would not be wise for Mercedes to head in to a race weekend without having completed a single lap on them.
Mercedes motorsport boss Toto Wolff told AUTOSPORT that the matter was still 'a work in progress' and that safety was an issue.
"When it is about safety it would be good if all teams are clear whether they [the tyres] work on their cars," he said. "But it is up to the FIA to decide.
"Safety is the priority for the FIA and I am sure they would safeguard that it is the same for everybody."
Mercedes team principal Ross Brawn has admitted, however, that Mercedes' only real chance of getting some running would be if the test ran into a fourth day - something that is unlikely to happen.
"If it was extended to a fourth day then we would have an argument that the fourth day - an extra day- should be made available to us as our penalty was three days," Brawn said.
"I haven't heard the latest on what [other teams] are doing with drivers as it seems to vary.
"We certainly won't be able to attend the three days and it doesn't look like it is going to be extended."
The FIA is expected to clarify its position on the young driver test later this week.