Why don't trucks go 55 for fuel efficiency?

***** Extra Credit*****


I've had my APU on for like 25 hours. How many hours of wear have I put on my engine and after treatment system?

 

To play devil's advocate here, it is still true to say that in your example truck#2 will waste less time to burn whatever amount of fuel is needed to cover the same distance. Which might turn out to be a better outcome, nonetheless.
Trying to be a smart ###.

 

Just don't!
My brain still hurts trying to grasp his idea.

 

Sometimes these things - physics laws, are more counterintuitive to people due to the way they feel them.
One more theory that I heard, to which I decided not to find an argument was that when you travel at higher speeds, the vehicle burns less fuel due its higher momentum. The velocity and mass will plow through the air resistance at better efficiency thus, supposedly, burn less fuel than a vehicle with a lesser momentum, struggling with a head wind in a more effort absorbing way.
I was going to ask the other party if that means that a freight train would burn less gallons of fuel than his truck covering the same distance under the same weather conditions ( even if they mattered) but decided not to pursue the subject out of diplomatic reasons. As the fellow was in front of me at the fuel island and surely he would have persued the subject even further and I was ready to go.

 

How can it burn less fuel at a higher speed when the faster you go the more energy you need to push the truck through the air?

There have been studies that show for every one mile per hour over 55 you lose one tenth of a mile per gallon. Using @Hammer166 ’s example above was a simple way to explain it but the same truck and same driver with the same load on the same road would never have the same fuel economy when one trip was 15 mph faster. I’m not smart, I’m just a truck driver, but I do know it takes fuel to push a brick through the air.

 

This is too funny. Found this old Instagram post from 2017 and according to the caption I had 4 hours to kill and stopped to take my dog for a hike. Pretty sure this was not a 19 hour day on my electronic log. Lol

 

we (when i was working) keep up with the flow of traffic. too many others are going to ram into our donkey's if we drive too slow.

 

Putting theory and studies aside, sometimes I go slower, sometimes I go faster but the most 'visible difference' in mpg I see only when I am light vs heavy.

 

You're absolutely right. I did it that way too show that travel time had zero effect on fuel burn, which was opposite of Snowwy's ridiculous premise.

 

My speed and mpg’s depend on if I’m hungry or can get loaded/unloaded early or if I wanna shower or if mama is waiting for me or if I have to use the restroom. Hahaha