QualifyingThe 2005 grid will be decided by two qualifying sessions,
one on Saturday afternoon and a second on Sunday morning.
The single-lap format introduced in 2003 remains –
but the twist is that the grid will be decided by adding together
a driver’s times from both sessions.
Cars will run with low fuel levels in the Saturday session,
going out in reverse order from their finishing positions at the previous race.
On Sunday, the running order will be decided by the results
of the previous day’s session, with the fastest car going last.
The decision to use aggregate times from both sessions means that a driver’s
raw pace on empty tanks will now contribute to their position on the grid.
This means that race strategy will arguably have less influence on the
make-up of the grid than it did before.
TyresPut simply, drivers will have to use the same set of tyres for qualifying
and the entire race distance.
A tyre can only be changed if it is punctured or damaged.
As in previous seasons,
drivers will choose from two tyre compounds after Friday practice.
However, once this choice is made, they will only be allocated three more sets –
one for Saturday morning practice,
one for qualifying and the race
and an additional set in case of a puncture or accident damage.
Needless to say, 2005-spec rubber will have to be much harder
than in previous seasons, while drivers will have to conserve their tyres.
This should benefit smoother drivers such as Jenson Button.
AerodynamicsThe FIA have tweaked these rules in a bid to reduce downforce.
The most noticeable of these changes are to the front and rear wings.
Front wings must now be higher, while rear wing elements must now be
further forward on the car.
The FIA has also clamped down on rear diffusers.
While the FIA hoped that these measures would reduce downforce
by around a quarter, in reality the teams are already beginning to nibble
away at this performance deficit.
EnginesEngines must now last for two full race weekends,
as opposed to one in 2004. That means a driver is unlikely to clock up anywhere
near as much mileage in practice.
As in 2004, a driver changes engine ahead of qualifying,
they will drop 10 places on the grid.
Should an engine be changed between qualifying and the race,
they will be sent to the very back.
If an engine is changed, the driver must use that particular power unit
for the whole of the rest of the weekend and the next race.
But if a driver retires with an engine failure during a race,
they will not be penalised at the following event.
But beware – some things, such as the qualifying format, may change again! 
