Parc ferme is an enclosed and secure area in the paddock
where the cars are weighed and any other checks deemed necessary by race
officials are made. Teams must leave their cars here from within three
and a half hours of the end of the qualifying on Saturday until five
hours before the start of the formation lap on Sunday.
the cars are deemed to be under parc ferme conditions for a much longer
period - from the time they first exit the pits during qualifying until
the start of the formation lap immediately prior to the race.
these conditions, the work teams may carry out on their cars is limited
to strictly-specified routine procedures, which can only be performed
under the watchful eye of the FIA Technical Delegate and race
scrutineers. Fuel may be added to the cars, tyres changed and brakes
bled. Minor front wing adjustments are also allowed, but little else.
These controls mean that teams cannot make significant alterations to
the set-up of a car between qualifying and the race.
exception to this is when there is a "change in climatic conditions",
for example a dry qualifying session followed by a wet race, or vice
versa. In this case the FIA will give the teams permission to make
further appropriate changes to their cars.