F1 teams have expressed concern about the latest version of the 2021 technical rules.
On Monday, they were presented with the latest concept of the 2021 car, codenamed 'Lima'. The main difference compared to the earlier version is a more elegant front wing.
But Auto Motor und Sport claims some teams have calculated that the 2021 concept produces 60 points less downforce than the current cars, amounting to about 6 seconds per lap.
The FIA's Pat Symonds denies that.
"It will certainly be less than that," he said.
However, it is rumoured that Sergey Sirotkin was three seconds off the normal pace with Pirelli's 18-inch tyres at the recent Paul Ricard test with Renault.
Not just that, the teams are worried that the rules are far too restrictive.
"I doubt there's any aero department that's read those rules and got particularly excited about them," said Red Bull's Christian Horner.
However, F1 sporting boss Ross Brawn played that down, insisting: "The good teams will still be in front. The gap to the back of the grid will just be smaller."
After a delay, the final regulations will be handed to the teams on October 31, with the public set to be shown the concept in detail a few days later.
But rumours remain that the teams may not sign up for the new rules.
Asked what would happen then, an unnamed team boss answered: "We would just have to continue with the old rules."