Headlights on LeMans/LeMans Endurance Series (LMES) cars

Sharp eyed viewers will notice that some of the cars fielded in LeMans-type events have yellow headlights. Originally I wrote this off as being a european oddity; however the rules state that GT cars should have yellow headlights, while the prototype cars would have white lights.
The cars are not restricted in how the field of light is spread in front of the car.
The rules state that the driver must be able to flash lights across the front of the car; typically this means that the cars have four lights (two on each side of the front of the car); usually only the inside or outside pair of lights is flashed. This lets the driver signal to other traffic that they are passing without turning all of their lights off at the same time.