On the green light side what ever my orientation is. And that is the side the NPCs mostly use.
I say mostly, as today I witnessed first time an NPC leaving a station from red light side (without this poll I most probably would have not paid any attention to this, now I was like "???"

. However, immediately he exited the slot a fed started to tail him, for which the NPC responded "Is there a problem officer?", no seen reaction from the fed. I have never seen this before. So I am guessing that the feds outside the station are monitoring also that you are following the rules, and if you want to avoid fed scans you should use the green light side or else you will get feds attention. If this is true I am not surprised if speeding has the same result.
I tested it during my Vennik runs intentionally going in and leaving out on the red side, but my samples are too small to get any reliable result. I could not check my six to see if this behaviour draw any attention of feds. Scans happened only on red side though.