Is there a scientific chart showing how much fuel you save by going slower?

If your freight doesn't pay enough to justify running at the speed limit. Your hauling cheap freight in my opinion.

 

i could be wrong but image most do bassed on delivery times and real world driving time so your not stuck somewhere twiddling your thumbs middle of no where waiting to get unloaded. Less stress trying to get in front of the next car and truck and saved money is a added bonus

 

I didn't think this would happen.
1. To the fella on the e-logs
A. I will be leaving the industry at that time.
B. Cheating logs- I don't cheat, I don't drive anymore hours or miles total in one day than you.
C. Clogging up lanes- At the speeds I run I know where to be. I won't be the one clogging the middle lane in a 3rd. lane restricted area.
D. Freight rate- my rate is $2.50 to $3.00 gross. I have ran some cheaper stuff at times the last two years. I don't make a steady diet of it.
The reasons I run at a slower speed, so that I can profit more to the house. My house, I like toys and nice things.
If I can slow down and put an extra 10-15,000 in MY pocket, hell yeah.
I have an '03' that I maintain that hasn't cost me more than maintenance in a few years ( knock on wood)
I take my fuel mileage at all fill ups because I think it is like checking fluids, the pulse of the truck, knowing your equipment.

 

Its best to figure it out for your truck, because your rolling resistance, aerodynamics, gearing, & engine are going to be different than whatever chart you find.

Cruising on flat ground I get roughly:

11mpg at 50mph & 1200rpm
10 at 55 & 1300rpm (10% faster, 9% worse mpg)
9 at 60 & 1400rpm (9% faster, 10% worse mpg)
7.8 at 65 & 1500rpm (8% faster, 13% worse mpg)
6.5 at 70 & 1600rpm (8% faster, 17% worse mpg)
5.2 at 75 & 1700rpm (7% faster, 20% worse mpg)

This is just the fuel consumed while cruising -- overall trip mpg doesn't fluctuate nearly as much because you burn the same amount of fuel idling, almost the same fuel accelerating, almost the same fuel going uphill, almost the same fuel downhill, etc.

If I had a 13 speed, or a tractor with side skirts, or a trailer with a tail, etc I wouldn't get much better mpgs at 55mph, but would do significantly better at 70+.

 

If you are driving 62 and logging 66 you are cheating plain and simple.

 

I get 8.9 at 58 on flat ground. I get bored. I get 6.4 at 75. I need to govern myself. I lack a certain amount of self control.

 

Ok

 

It's put it to you this way.

"Fuel Burn per Hour" If you had a large horse engine, you don't need as much fuel to do the same work accelerating and maintaining road speed minus the parasitic loadings of all kinds at the wheels. But god help you if you had a whipped 280 or something from the 60's and you will empty your tanks several times a day. It's not worth it.

Put another way.

A Big Cam 4 from the early 80's would do Town Hill south of Breezewood loaded 80K right about 19 to 21 or so mph. It's 5 miles to the top on I-70. All out maxed rpm etc. Not quite enough torque to catch the next gear up and stay lugging. It will fall off because the gearing was too tall in those days.

Throw in a 350 Mack CH modern make roughly 1990's it will do the same hill at 45 at above torque and not burning much fuel because it is not at 1550 or whatever rpm is high horse on your power curve chart.

However...

There is a hill in Vermont I put a 350 CAT against it loaded with Ethan Allen Furnature, hardwoods stuff, heavy as sin. The CAT informed me that I was consuming around 30 gallons an hour during the pull. I checked the fuel remaining in my tanks and found that I will have a thirsty truck before I get out of the Northeast because of that pull.(Only had like a 130 gallon tank. Not the 300 plus that we were have later in my years) It was disgusting. The grade was 21% 3 miles, took about a hour and change less than walking pace to lift it straight up and over. And 2 plus hours before all the gauges returned to what I considered normal.

In Aviation, gallons per hour burned is what we used quite a bit. It is easier to stay at a flight level or to glide down in a descent than it is to lift a place to altitude. It requires more fuel.

A long time ago I recall a Article written in a Newspaper I think was called "The Trucker" and in that writing was a demonstration of two trucks. One ungoverned and cannonball from westcoast to Boston and the other legal speed all the way to Boston. Both left at the same place and time.

The faster truck clocked in approximately 30 minutes to several hours average gain each day over hundreds of miles but the legal speed truck like a slow steady never ending relentless pace erased the fast truck to where both rigs arrived in Boston pretty close to one another.

It was nice to be fast. Make time. But you can lose all of it in a hurry in some traffic jam or something. Pof.

By the way our Team truck 2001 fuel per mile average a shade over 6.5 and that is being constantly against the Governor at 63 24/7 for 300 plus days with a few record days approaching 12 to 13 plus miles per gallon eastbound coming into Kansas from Limon when the wind is right on our rear. This is with a Detriot 500 and a rockwell auto Company truck century. Or thought of another way approximately 85,000 in fuel cost with revenue that must approach a half million dollars. Or put a different way, how many accounts saved by snatching failed single drivers and racing the loads in before the threats from Customer became reality.

Before that Ive had trucks like a Freightliner FLD 120 with 320 gallons full and the same but older 500 Detroit from the early 90's do 1600 miles on the entire load of fuel from the NW coast down 5 into Arizona. That was a interesting day because at that time Californa was not a suggested fuel stop then. I knew we could do 1600, just have to prove it. Thinking back, small changes in RPM and shifting would try for 2000 miles in the right situation somewhere else in the USA.

 

If you are picking your own loads you may occasionally need to run the speed limit just to preserve your 70 hour clock, depending on what loads you have stacked.

 

Please explain how it is not. Also why quit just because of Elogs if as you say you run "legal" and save "10-$15,000 a year.