I don't know who photo-edited the following picture, because I'd like to shake his or her hand. At the very least, I'd like to give him or her credit for the work.
But the signs hit the nail squarely on the head:
Having driven several highways over the years, these rules have been my mantra on the road.
Same does for speed. People: when you're on the highways, pick a speed; any speed. Just stick with it. If you don't have—or don't know how to use—cruise control, just keep an eye on your speedometer. No one wants to play leapfrog with you. If I pass you on the highway, I don't want to see you race past me later on, only to have me pass you a few minutes later. If you pass me, that's fine. I don't expect to catch up a few kilometres on.
If you can't keep your speed constant, get off the road. Turn in your license.
That is all.