But does anyone know the reasoning for the yellow-colored headlight lenses on the racecars?
“In 1936, the French for tactical reasons wanted a way to identify the registration nationality of vehicles at night. However, they did not want to reduce roadway safety, and wanted in fact to improve it if possible. So, they figured to remove the blue from the output spectrum of their vehicles’ front lamps. White light with the blue component subtracted is known as “selective yellow” light. It is a pure yellow color with little or no orange component—hence the French yellow headlamps. Yellow lamps have consistently over the years been subjectively ranked as better in poor weather and lower in glare than white ones, but is the effect real? Or is it just a subjective impression?”
…lengthy article on the subject here [LINK].
I thought the yellow headlights denoted GT class cars (faster classes white) so that the drivers at night at events like LeMans know what class car is behind them. I’m not an expert on European racing by any means, so I could be way off.