Keep in mind our highways are notorious for being deeply rutted from the use of substandard surface asphalt on the 100 series highways.I just pulled in to Halifax from Ottawa. While the posted speed limit in Ontario and Quebec is 100kmh, it is 110kmh in New Brunswick and Nova Scotia. Hitting 130kmh and more in Ontario and Quebec was dead easy. Once we got to New Brunswick, despite the great condition of the main highway, despite the fact that it was largely empty (dream on, you who prowl highway 400), it was an absolute bugger to hit and maintain 120. Now, clearly part of that is the hilly nature of NB and NS, but that wasn't the whole story.
Finally,it hit me: the lanes are narrower. Not by a huge margin, mind you. Maybe 2ft at most. But that shaves a metre or so off the total width of the two lanes on each side of the median. My wheels are straight, but I found I had to put in a little extra effort to stay in my lane, andthat was shaving off velocity.
I mentioned to my son the civil engineer, who was in the car with me: Are these lanes narrower or what? And he replied that it is a known strategy to narrow lanes as a speed-calming measure. In some respects, the posted limit of 110 is almost a dare from the respective ministries of transport: "See if you can keep this up, sucker!".