Just unlocked Nurburgring and went to Arcade to play it. Chose time trial, night race. When it starts to get dark, my lights don't come on. I've searched for a button but can find nothing other than low high beam.
If it's a Standard car, what you see for lighting is what you get. If you're in a Premium, you can select high-beams. On a DS3 and DFP, it's the R1 button. Pressing it in the daylight also makes them flash.