In an ideal world tyres would never wear out and you wouldn't need to refuel.
But in Indycar racing tyres  last about sixty laps,
and the seven-hundred horsepower 3. 5 litre V8 engines burn up about two gallons a lap!
So during the course of a race you have to pit.
And the quicker you are the more chance you have over your competitors.
This guy's about to make a pit stop.
He's going to be pitting under a green flag, while the race is in full swing, so he must be at the end of his pit window.
You have a number of pit windows throughout the course of the race,
but don't worry too much about when to pit, as your pit crew will let you know when it's time to come in.
The general rule in Indycar is to follow the leader so he should be able to make a pit stop without losing any places.
The next time you're racing, if the leader pits and you're on the same lap then you should pit too,
regardless of whether you're in your pit window or not.
As not doing so will place you out of sequence with the race leader.
The only time you don't want to pit when the leader pits
is if you were a lap or more down, so you could catch up.
But this is a gamble.
You're gambling on there being another caution period in the near future so you don't have to pit next time under a green.
Now when you enter the pits you need to make sure that you don't speed keep it under sixty miles per hour.
You won't save yourself any time by speeding because you'll be black flagged
and this will cost you more time when you return for your penalty.
Approaching the pit lane focus on your speed making sure you slow down in time.
But make sure you don't slow down too soon either,
you want to hit that pit speed limit line bang on to get the quickest pit stop.
When travelling down the pit lane, you can tell your crew what you want done to your car.
You can specify how much fuel you want to take on board,
whether you want to adjust your front wing, and whether you want a fresh set of tyres.
As a general rule you should always change your tyres,
but if you want to shave vital seconds off your time you could choose not to.
Remember the more your team does in the pits the more time it will take to pit you.
Your pit crew can also perform minor repairs if you have taken some damage
but be careful, if you smack up your car too bad then you're out of the race.
So you've entered the pits quickly and without speeding,
your pit crew have performed exactly what you wanted.
Now you need to exit the pits and get back out there into the race as fast as possible.
Once you've left the pits you can speed it up.
Feed the throttle in gently, or you're likely to spin as you've just got a set of fresh cold tyres.
You also need to stay in the warm-up lane until you're up to race speed.
Keep an eye out there for the blend line;
your spotter will let you know when it's OK to blend back into the race.
And keep an eye on any approaching cars.
OK for this test we are going to simulate a full pit stop.
Just as before the race leader is going to pit during a green flag.
You'll be in the middle of the pack and will also come in for a pit stop.
Get into the pits as fast as possible but remember not to speed.
Set your pit options and once your crew has finished get back into the race as soon as you can.
You need to get up to race speed before blending back into the race.
To pass the test you must not lose any positions by the time you rejoin the race so you need a good quick pit stop.
It is a lot easier to gain positions in the pits than it is to pass someone on the racetrack.
Three, two, one, GO!
That's an OK pit stop and you didn't lose any places. Bronze award.
Good pit stop, good time. Silver award.
Excellent pit stop and that's an excellent time! You just won the gold.
That was close, but you're still not fast enough.