Formula 1 teams have agreed a tweak to the sport's testing regulations to prevent anyone gaining a benefit from using 'filming days' to try out new parts, AUTOSPORT has learned.
The strict in-season testing ban means outfits are not meant to try out new parts away from a grand prix weekend.
However, some teams - including Mercedes GP with its new engine cover design and Ferrari with its blown diffuser - have this year managed to complete some limiting testing under the guise of a 'filming' day.
Those runs caused some concern among rival outfits, and teams have spent the last few weeks trying to tidy up the regulations.
Sources have revealed that at last week's British Grand Prix teams got together to sign off a new testing agreement that will prevent teams from exploiting filming days.
AUTOSPORT understands that with immediate effect, teams will be banned during filming days from running any parts that have not been raced before.
McLaren team principal Martin Whitmarsh confirmed the changes had taken place, and was pleased that everyone was now in agreement about what was and was not allowed.
"I personally did not feel there was any ambiguity, but others argued that there was," he said. "But that is pressure, and when people are under pressure they try and take a different view.
"It is now clear that, if you are doing a demo run, then you must use components that have been raced before - and it has to be a legitimate demo run."
Although the filming loophole was still open ahead of Silverstone, Whitmarsh revealed that he ruled out his team making use of it for its new blown diffuser, despite some pressure from team members.
"The engineers here said others have done it, why can't we?" he said. "My view, as someone trying to hold FOTA together, was that I felt we could not take that advantage."