Red Bull and Lotus could join Force India, Caterham and Marussia in sitting out the opening winter test at Jerez beginning on Sunday.
Italy's Omnicorse claims Red Bull, whose designer Adrian Newey customarily pushes the boundaries with his new-car deadlines, has this week failed a front impact test at the FIA-approved Cranfield facility with its 2015 car.
If true, it means the new Renault-powered RB11 cannot be homologated and therefore tested at Jerez until the FIA approvals are met.
The report said: "It seems the RB11 has a very short nose with a short bulb at the front that has failed the test."
Omnicorse said modifying the design should not be a major task for Red Bull, the champions of 2010-2013, but it could mean time runs out to get the car up and running on the opening day of the Jerez test on Sunday.
Trouble for Lotus as well
Meanwhile, Turun Sanomat correspondent Luis Vasconcelos reports that Lotus could be yet another notable absentee when Jerez action gets underway.
He said a problem with a carbon supplier means the "first monocoque was finished only last Friday, giving the team very little time to build the car around it".
And Vasconcelos claims that when the Mercedes-powered E23 does make its Jerez bow, it will have been put together with a considerable amount of 2014 components, meaning that "in essence, the new car will only debut in Barcelona on 19 February".