Why Do F1 Drivers Zig-Zag?

Pirelli tyres are designed to give optimum performance at a temperature between 100-110 °C. It is for this reason that the tyres are wrapped in heating blankets before the cars take to the racecourse. Between the time the cars leave the pits and the start of the race, the tyres cool down. Zig-zagging is a way to keep the tyres hot and even heat them up further if possible.
 
Every F1 driver wants to get off to a good start. A good start is the first step to having a good race. Tyres at an optimum temperature give the car a good grip on the track. Cooler tyres are likely to skid when taking off for a high powered start. Hot tyres ensure a good start and possibly a lead going into the first curve of the race.
 
It is crucial that the drivers keep the tyre temperature up. The formation lap is so slow that tyres tend to cool down. Drivers also brake sharply to raise the temperature of the brakes. Zig-zagging not only maintains or increases the temperature of the tyres but also wears the new tyres slightly. A slightly worn tyre at an optimum temperature will give a better grip on the track than does a new tyre.
 
Zig-zagging and braking helps to increase the temperature of tyres and brakes. Having the tyres and brakes at optimal temperature is crucial for drivers to get a good start.

Tyres that F1 cars use are designed for gripping the tarmac and are very sticky. A lot of small pieces of rubber are left behind on the track from the previous practice and qualifying sessions and races. Besides these, pebbles, sand and grit may be present on the track. The speed of the cars in the formation lap is so slow that the tyres tend to pick up the debris.
 
Accumulation of debris on the tyre surface tends to reduce the grip of the tyres. At high speeds, the accumulated debris is also likely to damage the tyres. Zig-zagging helps remove the debris the tyres might have accumulated at the slower speed of the formation lap. Going from side to side helps to rub off the debris from the tyres.
 
Drivers often zig-zag more vigorously toward the end of the formation lap. This manoeuvre helps to remove the debris from the tyres’ surface while heating them and preparing them for a good start.

When racing, the rules forbid drivers from swerving from side to side to protect their position, as this is dangerous and can cause crashes. The leading driver can move their car once, but any more than that and they will receive a penalty.
 
More zig-zagging is often seen in the first lap when the cars are battling for position. It may also be observed during a safety car period. At slower speeds tyres cool down faster, so zig-zagging puts more energy through the tyres, which warms them up and gets them closer to race temperature ready for the restart.

Formula 1 cars are speed machines that are designed and built for maximum efficiency. Their weight is the deciding factor in the speed that they achieve. FIA regulations stipulate that the car should weigh a minimum of 752 kgs including the weight of the driver. There is not much the team can do about that but the car is also filled with an additional 110kgs of fuel.
 
An F1 car does not need 110kgs of fuel to complete a race on any course. So the car ends up carrying an additional weight which slows the car down. The fuel consumed by the car is continuously monitored by sensors and the data is fed to the team crew and the driver. Team engineers carefully note the amount of fuel the car consumes per kilometre of distance.
 
The above information allows engineers to calculate exactly how much fuel the car will use till the end of the race. The engineers instruct the driver on how much fuel he can shed and complete the race. The driver tries his best to shed as much fuel as he can during the formation lap to get a good start.
 
As the car engineers know exactly how much speed the car will gain per kilogram of fuel burnt, drivers do their best to burn fuel. Burning fuel is an exercise towards getting a better start as well as more speed during the race.