This can be done at the very start of a Grand Prix - during the dash towards the first corner - or during the race itself. Although you will often hear talk of cars ‘overtaking in the pit lane’ (meaning a car gaining track position through a better pit stop compared to a rival) this is a matter of race strategy. Most people regard overtaking as meaning cars passing each other on the track, during the race.
This sort of overtaking is brought about by a speed difference: the car behind going sufficiently faster than the car in front to make a pass. The higher the speed difference, the easier the overtake. As Formula 1 cars are typically very closely matched on performance and because braking distances are comparatively short compared to other forms of racing, overtaking often requires a great deal of skill, commitment and courage.
An innovation that makes the driver’s task slightly easier is the Drag Reduction System (DRS) overtaking aid. Within designated DRS activation zones, a driver within one second of a rival car may activate his DRS. This alters the angle of the rear wing flap, reducing drag and thereby providing a temporary speed advantage. To ensure that overtaking is not too easy, the length and location of DRS zones are carefully controlled.
Outside of the DRS zones, drivers can use several other methods to try to get past an opponent. One is to utilise an aerodynamic ‘tow’ from the car in front. This is achieved by moving into an opponent’s slipstream – a pocket of low-pressure air behind a car through which the following driver can move more freely and gain a small speed advantage. However, whilst useful on straights, this aerodynamic effect is problematic in corners as the reduced airflow acting on the wings of the second car will dramatically decrease aerodynamic downforce, and hence grip, meaning that the car behind will typically be forced to drop back, or to pick a different cornering line in 'clean air'.
If a driver cannot complete a pass on a straight, he may elect to overtake into a corner under braking. This requires an enormous amount of skill from the overtaking driver - not only is he likely to have had to move off line on to a more slippery part of the track, he must also judge how late he can leave his braking. Get it wrong and he could overshoot the corner, spin off or - worse - make contact with the car he’s trying to overtake. As you might expect, tyre grip often plays an important role in these situations, with a driver on newer tyres having an advantage. Similarly, a driver on fresh tyres will stand a better chance of overtaking the car in front in the traction zone out of a corner, particularly if he’s set up the move in advance by taking a different racing line into the corner.
A driver trying to fend off an overtaking move from an opponent must rely on his ability to pick the correct braking points and cornering lines. A skilful driver can also hold off an opponent by adopting a defensive yet legal driving style. Typically this means reducing the angle available for the car behind to use going into corners where there is a substantial risk of being passed. Providing that the driver ahead only changes his line once going into a corner (not deliberately attempting to block the car behind) this is a perfectly justifiable form of racing, and with it a driver in an inferior car can successfully hold off a faster rival.
Narrowing the car behind's angle through corners can also force it to take a later apex and even run wide, even if it has successfully made the pass - and this can result in the slower car getting back in front again. A side-effect of this defensive driving is that it tends to slow both drivers down.
Great overtaking moves represent F1 racing at its very best - poor ones can bring the sport into disrepute. It's a tribute to the incredible skill of modern drivers that they are normally able to race extremely closely and fairly without making contact, but officials are always monitoring overtaking attempts, and any dangerous driving - whether attacking or defensive - will see the driver called before the stewards and penalised.