Perhaps the SLEx people should put signs with speed limits and vehicle types appropriate for each lane. I doubt though that this would be enough to curb the motorists who hog the passing lane.

And speaking of signs, I find the signs on the NLEx a bit too small. You need to be quite close to see it and by the time you do, you would already have passed your exit. They charge so much and yet scrimp on the sign size. They probably do want you to pass your exit so you'd gave to double back and end up paying more toll fees as well as burn more fuel.