I agree that many of us don't obey the speed limit, but here's an excerpt that stuck out to me:
"Consistently, the 85th percentile loses out to the perception that faster roads are less safe, so speed limits should be low. It’s a misconception, Lt. Megge says, that he faces often in his work. When he proposes raising a speed limit, the initial reaction is always “Oh my god! You can’t do that. People are already going too fast.” People think raising the limit 10 mph will lead people to drive 10 mph faster, when really changing the limit has almost no impact on the speed of traffic. "
Well, we raised the speed limits in CA about a decade ago from 55 everywhere to: 75 outside heavily populated areas; 70 for inter city traffic and 65 for local freeways. The average speed of traffic has gone up 10mph above the posted limits.
Local roads still have speed limits of 25,30,35,40,45,50 and 55, but the freeways are really fast when there are less cars on the road (i.e., not during "rush" hour).
I'm not going to admit to any of my driving habits, but I do drive safely and in line with everyone else on the road.
One day, when I had a lot of time to kill, I decided to go exactly 60mph (the posted limit). People were passing me pretty fast. I was on the right most lane too. In any case, my mpg rating went from my normal 27mpg up to to 37.5 mpg. I was pretty amazed that the same car going 60mph versus, ahem, my normal driving speed could attain that much more efficiency. Not sure what it would do to my 245hp engine (Just a normal car around here.), if I sustained this behavior.
There was a definitive improvement in the efficiency, albeit a limited test. I don't even dare try 55mph, because I almost with certainty would be rear ended by a U-haul truck with the trailer attachment going significantly faster than the trailer speed limit of 55mph.
So, anyone thinking that people will not drive faster with faster speed limits does not understand human behavior too well.