There are several statements that I have issues with. And of course there is also the taxpayer funded propaganda that I need to address as well. Different vehicles have speeds at which they are the most efficient. Hybrids and electric vehicles usually are more efficient at lower speeds, while many internal combustion engines are more efficient at higher speeds/rpms. There are many factors that affect efficiency trends. I used to have a Suburban that was most efficient between 90 and 110 mph (over 20 mpg), while at 35 mph, it only got about 13 mpg (both at fairly constant speeds without stops between origin and destination). Where you get the most loss in efficiency is when you use your brakes. Vehicles that are equipped with turbochargers or superchargers are more efficient at higher rpms than vehicles that are naturally aspirated, but at lower rpms they are about the same. The transmission gearing and type also make a huge difference. My old Suburban was geared high and had tall tires so that at 100 mph it was humming along nicely at around 2000 rpms, and since it had a locking torque converter, it didn't lose efficiency there. My step dads little Honda was taching out at about 80 mph in it's top gear and the engine sounded like it was screaming, so obviously it was designed to be most efficient around 65 mph. If a vehicle's cam shaft is shaped so that the valves are open longer, it will be more efficient at higher speeds than one that holds the valves open for a shorter percentage of the time.
I was wondering what you think constitutes "dangerous driving". I think it is many things to many people. I usually don't "weave in and out of traffic", but I have found that I am more likely to do it on MA highways because most of those folks don't seem to understand the concept of lane courtesy. When I do change lanes, I use my turn signals and because I am going faster than the vehicles that I cut in front of, there is no need for them to apply their brakes, and unless they stomp on the gas, they won't hit me. I usually keep a comfortable distance between my car and the one in front of me, but sometimes when a driver forms a rolling roadblock by traveling in the left lane of the highway at about the same speed as the car(s) to their right, I close in and try to persuade them to get out of my way. The best way to keep traffic moving smoothly and safely is for drivers to keep right except to pass (which is the law in MA, but is rarely enforced). In NH, if you are traveling in a lane other than the far right lane, but are not passing someone, you must yield to the right if another vehicle approaches you from behind. Maine has a similar law. When I was a teenager, I actually got pulled over in MA for driving in the passing lane when there were no other vehicles within sight, except for the cop who was waiting on the side of the road. Whether or not it is the law where you live, please keep right except to pass, unless you will be taking a left turn soon, and yes, it's still considered passing if you are moving into the second lane so that traffic can merge onto the highway from an onramp. When drivers drive faster on the highway, they spend less time on the highway, which results in fewer vehicles on the highway at any time and less congestion.
A recent study by the NHTSA concurred with my personally observations and showed that more accidents occur at lower speeds, with most accidents caused by inattention. The only "accident" that I have been "at fault" in was caused by a u-joint failure in the poorly designed rear driveshaft of my Jeep Wrangler, which cause my driveshaft to fall out while I was driving down the highway. The driveshaft bounced off the road, then the Mustang that was behind me, flattening one of his tires. I have been speeding for the last 15 years without hitting anyone. Several of those years I was a professional driver, working as a chauffeur, courier, and truck driver, often driving more than 8 hours a day, 5 to 6 days a week, and usually over the speed limit. My wife also speeds, but she has been in a few accidents. She was driving very slowly while backing up (around 5 mph) in 4 of the accidents, and around 30 mph in the other. She admitted that she had turned around to tell the kids to stop doing something when she got in that one. All of her accidents were caused because she was not looking where she was going.
A number of years ago I had a motorcycle that was capable of exceeding 135 mph, and I reached that speed once. A late model Chevy Impala handles very nicely at speeds over 100 mph, and mine goes into triple digits almost daily when I am driving to work on the highway. When I am driving well above the speed limit, I make sure to scan the road well ahead of me and look for potential impedances or hazards. If it looks like there is a potential impedance or hazard ahead, I take my foot off the throttle well before I reach the proximity of the vehicle ahead of me and coast to allow my speed to match the vehicle ahead of me before I reach it so that I usually don't have to use my brakes. Fortunately in NH, people are usually more courteous, and are more likely to yield to the right than the drivers in the surrounding states, especially MA, CT, NJ, and NY. I would recommend getting a membership with the National Motorists' Association (
http://motorists.org), especially if you think that the posted limits are too low and are interested in making our highways safer and freer. As a former truck driver, the primary reasons trucks usually accelerate so slowly are because no truck driver wants to have to pick up skids of product that has fallen over because of a sudden change in speed, and the power to weight ratio in trucks is usually much lower than most passenger vehicles. When a passenger vehicle accelerates quickly, the gas mileage is worse during acceleration than when it is accelerating slowly, but the duration of poor mileage is also shorter, so there is not a big difference in average gas mileage between a vehicle that accelerates from 0 to 60 in 5 seconds, and travels a couple miles, and a vehicle that accelerates from 0 to 60 in 20 seconds and travels the same distance. The first vehicle gets worse mileage during the first 5 seconds, and better mileage during the next 15 seconds.