The FIA introduced a further tweak to the safety car rules ahead of Sunday’s British grand prix.
It emerged earlier at Silverstone that, following the post-Valencia furore, drivers would have to circulate no faster than the safety car while the race order is being determined upon deployment of the silver Mercedes gullwing.
The new slow pace was tested at the end of Friday practice at Silverstone, before a slightly faster pace was tried by competitors after another pre-British grand prix session.
But on safety grounds, the changes were scrapped a few hours before the race.
"The speed is just too slow," Pedro de la Rosa is quoted by Auto Motor und Sport. "If all the drivers don’t react, there could be rear-end collisions."
Robert Kubica added: "The accidents would be like the Webber and Kovalainen one (in Valencia)."
The German report said the only tweak that survived is the one where drivers in the last 200 metres before the pit entry are no longer subject to the delta time limits.
And race director Charlie Whiting said the FIA will try to only deploy the safety car when it can immediately pick up the race leader.
"An assessment will be made to determine when the safety car should join the track in order to try and ensure that no drivers will be unnecessarily disadvantaged," he said.