Refuelling stops

A Formula One car with a big enough fuel tank to do a full Grand Prix distance of 190 miles (305km) would be hopelessly slow. Not only would the car be very heavy at the start of the race, but it would also be aerodynamically inefficient because the fuel tank, which would need a capacity of around 330 litres, would have to be huge. The primary reason for pitting then is to refuel the car. During the fuel stop, teams also routinely check the tyres. As well as having fresh tyres fitted, the driver may take the opportunity of making other changes to the car while he is being refuelled.
The car’s handling may have changed since the car was set up before qualifying the day before. Maybe the car is now understeering too much for the driver’s liking. A quick cure would be to have some extra angle put on the front wing, something that can be accomplished in just a few seconds –usually less than the time taken to refuel.
The driver may have set his car up for the best possible lap time in qualifying, with quite high downforce levels, but he may now be finding that he needs more straight-line speed in order to defend his position in the race. In this case front and rear wing angles might be reduced. Again, this would take less time than is needed to refuel the car.
Depending upon the nature of the circuit and how much lap time penalty there is for a given weight increase, the main question is how many pit stops to make. Traditionally, most circuits have been best suited to two-stop strategies. However, the 2003 regulations stating that no fuel can be added or taken away between qualifying and race mean that three stops are now quite common in order to have the cars as light as possible in qualifying.