The term “g” is thrown around a lot in automotive skidpad tests to represent how much grip and speed it can handle. The results of the test is recorded in “g’s”, representing the amount of lateral acceleration (pointed in the perpendicular direction of traveling around the skidpad). Anything over 1 g is pretty respectable for a production car, and that means the car can produce lateral accelerations that match the earth’s gravitational constant. This also means that the driver is experiencing the force, proportional to their body weight, in that lateral direction.
When you move away from your everyday production sports cars and into something more open-wheel, like an IndyCar, you can expect the amount of g’s it can produce to go way up. As seen in the video below, a real-time output of a g-meter is shown while the driver takes the IndyCar around Phoenix Raceway. The 1 mile, low-banked tri-oval has been shown to impart up to 5.38 g’s on the IndyCar, per Graham Rahal, the driver of this IndyCar.
— Graham Rahal (@GrahamRahal) February 11, 2017
Just to put what 5.38 g’s feel like to the human body, just pretend there’s another 4.38 of you standing directly above your head. This explains why top drivers should be in peak physical shape. Not only do they have to withstand the mental stresses of concentrating around the track over an extended period of time, but their bodies also experience a great amount of physical stress, in all different directions, throughout the race. If you thought you raced well in Gran Turismo or Forza, try doing with someone pushing you around while cornering.