Formula 1 teams will not be allowed to use screens to hide their cars from fans and rival outfits during winter testing, following a rule change agreed by the FIA.
Though F1's regulations ensure teams keep cars on display during grand prix weekends, there has previously been no such restriction in place for pre-season testing.
That means teams, eager to keep their technical developments secret from rivals, have put covers on car parts or kept them completely hidden behind screens during the pre-season build-up.
At Wednesday's meeting of the FIA's World Motor Sport Council, it was agreed that a rule change be introduced that prevents teams from hiding their cars.
A statement from the governing body said the FIA had approved "Wording to prevent teams from covering their cars during winter testing, in order to make these events more appealing to the media and fans."
The new rules mean that the same restrictions teams have at grands prix will be in place during the time of track running at the tests.
Existing rules state: "no screen, cover or other obstruction which in any way obscures any part of a car will be allowed at any time in the paddock, garages, pit lane or grid, unless it is clear any such covers are needed solely for mechanical reasons."
There are also specific bans on engine, gearbox or radiator covers while engines are being changed or moved in the garage, covers over spare wings when they are on a stand in the pitlane, while parts such as - but not limited to - spare floors, fuel rigs or tool trolleys may not be used as an obstruction.
Some covers are allowed including transparent tool trays, rear wing covers to protect mechanics when firing up the car, tyre blankets and covers when it is raining.
Other changes approved by the FIA including rules regarding the sampling and testing of fuel at events to ensure they comply with reference declarations.
The FIA has also confirmed the appointment of three standard suppliers from 2021.
BBS will provide wheel rims, Magneti Marelli will produce fuel-primer pumps, and Bosch will supply the high pressure fuel pump and piping.