Why do some cars like the Koenigsegg CCXR have 4 pedals?

Answer 1

The Dead Pedal

The dead pedal is located to the left of a vehicle's pedal assembly. In a race car, the dead pedal is often an actual pedal that is "dead" in that it does not control any operation such as braking or accelerating. In many factory vehicles, the dead pedal is simply a raised area on the floor (or side of the floor) sometimes covered with a rubber slip mat.

The dead pedal is used by your left foot and accomplishes a number of things. First, it acts as a foot rest for your left foot when you're not using it. Second, because the area is raised, there is less movement required for your foot to go from dead pedal to clutch. In racing, this gains you valuable seconds and helps prevent the driver from placing their foot incorrectly on the gear assembly. Third, the dead pedal acts as support for your body under heavy braking, e.g. threshold braking during a race or emergency braking on the street. In these cases, your left foot braces against the dead pedal and prevents your body from sliding down in the seat (very helpful in a street car without racing harnesses!) Most importantly, this allows you more control over the brake pedal.

The dead pedal also helps prevent people from bracing their right foot in the wrong place during an emergency. Yes, believe it or not, many people will brace themselves by placing their right foot good and hard on the GAS pedal -- oops! Many times, when impact seems imminent, the brain says to the body "brace for impact dude!!" and freezes up. Sometimes, however, this freeze up happens when your foot is on the gas pedal. While the brain might have had good intentions, it certainly doesn't help accelerating into a crash! What the dead pedal does in these situations is allow the body to brace against something solid thus freeing the right foot to brake or accelerate away from a collision.