MPG VS. SPEED
 

Hello everyone,

I have been a company driver for three years, and now am considering becoming an O/O. My research is showing that slowing down, and adding certain fuel saving features to a tractor such as "Turbo 3000" will actually add more to the bottom line than speeding to each stop.

As an experiment, I drove from Lewiston, ID to Cincinnati, OH with about 45000 in the box, the entire trip I drove an average of 65 MPH, (Governed) and my fuel economy was about 5.9 MPG (2006 Freightliner Columbia) that trip took about 3.75 working days by the book.

On a similiar trip with same shipper and receiver, and about 44000 in the box but averaging just 57 MPH my Fuel economy rose to 7.0 MPG. BTW, I did cheat on the logs, so it took the same amount of time, but with shorter, more frequent sleep periods. :twisted:

My question: On a similiar trip in an older tractor, same make and model, and not governed I could theoretically get the load to receiver about a day sooner, but would it be worth it?

Ya, I agree with you. I try but I think about the time I waste on a long run. If I do 65 then I can do 600 in one day. If I do 57 then I would do maybe 550. Over a 5 day long run it will take me another 5 hours of driving or maybe a next day delivery if I run slower.

I do see the big savings on running slower though.

And about $200 in fuel savings, or $40 in hour(goes directly to bottom line".

So, I'd say you should look at every run particular situation, is it worth it?
Find the best compromise between fuel, speed and comfort!

And one other thing;-people who run faster, not necessarily drive more miles, and deliver earlier. But it sure cost them more to run it!
:wink:

It depends.

Do you have a nice hot lucrative load waiting for you where you will take your 10 and keep moving?

Or will you be waiting for a a day for a something to materialize?

I know speeding will be less painful if you have a aero tractor like a K660, Pete2000, Volvo VN or a Freightshaker Columbia.

Guys running @ 80 with a Classic Pete just tidybowl lots of $.

I know BUT the difference between 55 and 65 is like night and day. I fall asleep at 55 but at 65 it's a lot more fun.

look at it this way Lewiston, ID to Cincinnati, OH is about 2100 miles so
2100 / 65 mph = 32.3 hr's driving time
2100 / 57 mph = 38.8 hr's driving time
38.8 - 32.3 = 6.5 hr extra driving time.

2100 / 7 mpg = 300 gl.
2100 / 5.9 mpg = 355.9 gl.
355.9 - 300 = 55.9 gl.
55.9 gl @ $2.80 = $156.52 fuel savings

so it takes you 6.5 hr longer and you make $156.52 more or look at it this way for the extra 6.5 hr's you are driving you are making $24.08 an hr
it's up to you

That's why I've said;-"Find the best compromise between fuel, speed and comfort!"
Personally, i didn't drive 55 either, 65 is a good enough for me, and when it's roll, I'll let it roll to 75-80.
Also, in a few occasions, i will speed up intentionally, to break out of a wrong crowd...etc, very rarely, just for fun :oops: :D , but only for a short time.

Mostly, I'm having fun just to watch, the same trucks passed me 3-4 times, across 311 miles on I-80 in PA! :wink: :lol:

If you do 10,000 miles per month then you burn 1428 gallons of diesel at 7 mpg; or 1695 gallons of diesel at 5.9 mpg. That's 267 gallon difference which can translate into savings of $670 at $2.50 a gal if you drive slowly. So if you drive slow, you're putting extra $670 in your pocket WITHOUT DOING ANY EXTRA WORK!

I personally drive as slowly as possible, which is determined by the terrain and how heavy I'm loaded. If I'm bobtailing or pull an empty trailer, I set my cruise to - don't laugh - 57 mph (1,250 RPM on my CAT C15). If I'm loaded and need pulling power to go through some hilly terrain, I switch to 60 mph/1,350 RPM for more torque.

Just as the other driver pointed out, you'll be passed by Petes and Keywoppers but most of the time it'll be the same truck :)

Now that I'll be buying my own fuel I know I'll have to watch this, but I tell you on one of my last trips as a company driver I went from Oregon to Pa and I crossed the whole width of Ohio and it seemed like a four day trip at 55mph. Not to mention that every time I crossed into Arizona from California it felt like a weight off my chest.

Your truck will last longer if you go slow and easy.

I can't find it now, but I once had a copy of a study done by an economics professor and his class at a major university that studied speed vs. economy and its effect on owner-operators.

Their conclusion? The speed that an owner operator should go to get maximum results (cost/time/profit):

As fast as the truck would go.

-p.

And that study was probably done when fuel was $1 a gallon.

$3 a gallon fuel changes everything.

Not really! It just changes the final numbers!
And that study, was probably done on a paper, w/o actually considering reality. Which is quite different from the theories!

Anyhow, whatever makes you happy, I've done my own "studies", and come to my own conclusions! :wink:

MPG VS. ECONOMY
 

You know I didnt even figure in the savings in maintenance costs. I believe driving slower reduces wear and tear on the engine also, no matter what you have under the hood.

What do ya'll think about that turbo 3000 fuel atomizer, and centrimatics? any fuel economy savings noticed? thanks

Driving slower doesn't necessarily save wear on the engine. my reasoning is 60mph in my truck (12th gear) will do 65-ish in 13th gear, and at the same rpm. However, you'd be pushing a little more wind.

Going slow does sav fuel, considerably. 75mph across the west vs my last trip going 71mph yielded .5mpg+ increase in economy.

If you go slower, you can log it at the speed limit, but thats about as far as I'll go on that topic :wink:

The less horsepower an engine needs to make the longer it lasts. It doesn't have to do with rpms.

Re: MPG VS. ECONOMY
 

It depends.

For some components life is measured in hrs while for others it is in miles.

At my company our P&D tractors that don't leave town wear out steer tires every 60k miles with all the turning and backing they do.

I am very happy to see the peaked interest in fuel economy. I am a fuel economy junkie of sorts so I actually started learning how to wring fuel mileage out of my TDI VW just for the fun of it. So it does my heart good to see that fuel economy has become a thing of great interest.

There are several great articles out there on how to get the most MPG out of your truck. Cummins has this interesting article called "Dr Diesel's Secrets to Great MPG:
http://www.everytime.cummins.com/eve...Whitepaper.pdf

There is also an interesting diagram on the Paccar site showing some of the points of interest and relative percentages saved:

http://www.kenworth.com/brochures/FuelEfficiency.pdf

I always find it interesting how different drivers driving essentially the same vehicle can get huge differences in economy. The Cummins article points that 30% difference can be achieved in just the way you drive. I know I added a car computer to my car so that I could learn to drive the torque of my diesel and not the rpm. The savings is substantial once you learn the techniques, and of course slow down.

The other factors aside from your driving technique that can help is synthetic fluids, and tire pressures, and tire choice(all position tires everywhere). The aero is pretty much cooked into whatever truck you own. You can move the trailer forward. Kenworth says 36" separation for best results.

I find it funny that the engine manufacturers won't talk about fuel consumpution figures on the bench(take the driver and the other variables out of the equation). It is too bad that there are no EPA MPG numbers like you see for a car on big rigs. I would also like to see the CD(aero drag) numbers for a vehicle. Freightliner is talking about the Cascadia as being the slickest truck out there, but to look at it and thinking about how air moves and works I am not buying it. I would love to see some heads up aero comparisons with the latest aero trucks to really see what we are talking about as far as aero advantages. Fuel prices only go up from here and year over year I only see it continuing to trend upwards. It is time that more scrutiny is paid to these details. If you guys know of any aero comparisions on the big rigs I would love to see them.

Also I would love to see a formal rolling resistance standard developed for tires published. They have just danced around the issue in consumer car/truck tires and a limited amount of data is available. I haven't seen anything for truck tires. Has anyone seen anything like this for truck tires?

Longsnowsm

No kidding! I said the same thing about a year ago. We need these #'s to make a good business decision. Right now it's mostly luck. Which engine will be the best next year, nobody knows!

What you could do to eliminate all variables is put an engine on a dyno, and have it make 200 hp. Do about 10-15 different engines this way. The engine that makes 200 hp for an hour and consumes the least amount of fuel is your winner. 200 hp is 200 hp, it doesn't matter if its a 16 litre cat or a 10 litre cummins.

Looks aren't everything when it comes to aerodynamics. SAAB used to have very quirky designs that were quite aerodynamic but didn't really look it. Since SAAB started as an aircraft manufacturer, they knew a thing or two about aerodynamics.

Neither am I. Not to mention it's the ugliest truck I've ever seen. Hork.Me too. Very seriously.

cabovers were more aerodynamic then most conventional trucks, even todays aero trucks, it comes down to frontal area and how much of the truck actually grabs the wind.

I agree that the amount of frontal area is key to CD numbers, but it also depends on shapes and how the air is managed/moved out of the way. The cabovers have the aero profile of a barn door so I have my doubts about the CD numbers a cabover would generate compared to the more aero trucks. If anything I would think the weight advantages of the cabover would have a bigger impact than the aero. Again it sure would be nice to see some of this data.

That is precisely why I am doubting the Cascadia claims to the aero king. The size if the radiator area is huge(both tall and wide). The surface area is just too large, too flat, and the grill openings just too big to believe that there is an aero advantage here. Also I pay paticular attention to the rake and angle of the windshield and compare that to the one truck we know for certain was designed with aero in mind from day one the T2000. That rake of of the windshield and up over the cab is critical as is the movement along the sides of the truck. How that air moved and redirected is key. The Cascadia still appears to have much of the same profile of the Columbia in this regard. The Columbia actually looks more aero in the grill radiator area, but less along the fenders back side.

The only thing that appears interesting with the Cascadia is the way that the front fenders blend and fade into the body of the truck to smooth that air that would otherwise be turbulent over those fenders and along the doors. The typical shape would cause the air to be turubulent and roll and create turbulence, drag, and noise.

The other thing I don't understand is why the major carriers don't spec out the trucks with the side skirts to manage the air along side of the truck. Seems like a lot of the big carriers don't buy trucks with the side skirts. The numbers from KW seem to indicate those skirts do more than dress up the truck and should net a savings in fuel costs.

While I love the look of a long nose KW/PB, I am practical and as far as a truck is concerned it is all about the business and the money the truck earns/and I keep. So in my mind make a truck that looks like a bullet and as slick/efficient as possible.

The one thing I did find interesting on the Cascadia was the battery pack unit instead of an APU. That is an interesting thought, but the batterys will be heavier than a ICE that uses desiel. However with the no idling rules being extended to even APU's the battery idea may be the only real choice. Thoughts?

Longsnowsm

where`d you hear about the anti idling laws including apu`s?


the best way I can explain the whole aero thing is picture a columbia, the grille area is relatively small and gets wider as ya get to the back of the hood, the nose doesnt break the surface much and all that air ends up riding the sides of the hood all the way up to the cab, now on my 900 the grilles so damn big i`m punching a huge hole through the air and its not touching my hood but i`ve got so much other crap sticking out in the wind thats grabbing it, although in some cases the fuel mileage lost is neglible, i`m averaging 6.3mpg pulling a skateboard mostly in wyoming with 75mph speed limits, part of the reason for imo exceptional fuel mileage with a hood is tall rubber, real low (numerically) gears in the axles and alot more torque then the c15 came with, with alot more torque down low i`ll short shift up to 18th never going over 1450 rpm`s and cruise about 400 rpm lower then most other trucks.

Here is the rule that goes into affect in CA(2008) that effectively will ban the use of APU's unless they have emissions gear that is cleaner than anything currently out there:

http://www.ttnews.com/articles/baset...?storyid=17425

So I imagine this is why we are seeing the battery powered units showing up.

I have also read several articles and posts about people with APU's in anti-idling states getting finded for running the APU. I question how legal these tickets were and it sounds to me like ill informed law enforcement on the loose.

The laws in CA will filter across the rest of the country. It is only a matter of time. They don't care if your freezing to death or roasting in that truck. I think if they are going to go that far they should make it mandatory that all truck stops have shore power and at a big discount. I am surprised that this state doesn't get boycotted.

Longsnowsm

its already banned for me :lol:

Very interesting:

First of all

a) i don't see how a company driver will benefit from going slower in the long run unless you're getting a fuel bonus or something.
This is asuming you're not sacrificing safety by going faster. Which IS possible.


b)I've done a lot of number crunching and It ALWAYS benefits an O/O to go faster is it maximizes profit per week. Remember profit = revenue-expenses.
Yes, MPG will go down. But unless you're an idiot the load always pays more than what fuel and any other expenses costs. So the more loads you pull the more money you end up with.

Yes, maintenance costs go up (a little). Again read above.

Again, this is assuming you are not affecting safety by going faster. And there are ways to stay safe while driving 65-70 or more.

I'd love to see those numbers! :P

I bet Lewis Friend, err, brian griffin would love to see those numbers too.

I believe the California APU law is a CARB regulation. I doubt that the CHP and other local agencies are really going to spend a lot of time checking to see if APU units are actually CARB certified or not.

California is also banning reefers that do not have particulate filters on them! That's why the big companies are scrambling to put them on.

Wonder if anyone gave give me some infomatin. I am inline to purchase a unit from the company i work for. with all things equal i could get a 2003 with a c12 cat and 279 rears or a 2006 detroit with 264 rears. They are both set to 370horse. I haul glass and i wonder which would be the better pick in the long run.

Mr. Griffin,

I dont know if your an owner operator or not, but judging from your response that the faster you go the more revenue is made, I would say that your not. And if you are I imagine you'll be selling your rig before too long with the ever increasing prices of fuel.

Furthermore, the majority of drivers out there who consistantly speed in my observations are also the ones who follow other drivers and four wheelers way too close, and who are more frequently "forgetting" that they are suppose to be professionals.

I am seeing more and more so called "professional" drivers out here who are not using turn signals when they pass another vehicle, tailgating, and jumping in front of other vehicles before it is safe. I consistantly drive at 57 to 60 miles an hour and drive just as far as anyone else out here, (approximately 3000 miles a week) but I believe I am safer because I follow a little rule that seems to have been forgotten. That rule is: Do unto others, as you would them do unto you. Otherwise known as the GOLDEN RULE!

You know a little courtesy goes a long way.

Mr. Griffin, Please dont think I am accusing you of being unsafe. I dont know you, and you may very well be a very safe driver. The above commentary are just my observations.

for 5 years i would drive the speed limit or just over.. 72mph & 1850 is top end. ave m.p.g was 6.2 one day i decided to go slower. 60 mph & 53 mph in mi. yes it was painful :cry: but i did it. 7.8 mpg. all flat roads & approx 450 mi done twice same results. since then i keep cruise at 58-60 ave 7.2 hill, no hill, heavy light e.t.c. i had no idea the m.p.g would increase that much. & i dont use a/c/ or idle at all. unless bitter cold. i calculated if every trip was like the flat lander one's i would save over $600 a month in fuel cost alone. however if i have to get a load off to get another one on & can only do by driving the peed limit i'm hammer down. i'm not going to lose a $900 load to save $ 50 in fuel. but if i'm in no hurry it's right lane for me & i have plenty of company from scheider,swift, jb, & the others. :lol: by the way i have been driving the same truck for over 8 years. a 95 cabover wich just hit 1 mil miles months ago & still going with same engine, rears, & clutch. all original. nothing replaced. except one injector after it hit one mil miles..

The cost to run 70 vs. 60 is fairly easy to determine, just crunch the mpg numbers, toss in the improved maintenance costs, and it looks like a slam dunk, "run slow and more money flow"...

but...

What is the opportunity cost? The counter argument is moving faster means that you can turn more loads. More loads means more money. Hypothetically, that's true. In the real world though, the way that you'll run, is it? On a 2100 mile run, is 6 hours going to make a difference? Theoretically, do that 10 times and you've got another run in? Are you actually going to pack another run in?

exactly, it all depends on if you're on a tight schedule or not.

When your paying 550 to 650 every other day in fuel, I dropped my speed from 70 -75 mph and my fuel mpg was around 5.5, to 65 and my fuel went up to 6 - 6.5. Over the cost of the year, that amount adds up.

As far as wear and trear on the engine....sounds like the same to me unless your hammer down doing triple digits.

Maximum fuel economy (& minimal engine wear) for automobiles is 30 to 35 MPH (obviously there are exemptions with exceptional vehicles).

All things considered, higher speeds equal GREATER engine wear, SOCIALLY-IRRESPONSIBLE polutants *and* LOWER fuel mileage.

This is a no-brainer.

God Bless all

I don't think so..... speed has absolutely nothing to do with MPG or engine wear. But has everything to do with the type and setup of your engine, transmision and rear-end ratio's.

For instance in my 2003 Jetta it is a 2.0 5spd. 30-35 means I'm over revving 3rd gear or lugging 4th gear and both are hard on your engine and both waste fuel.

Uh yes it does, speed increases the horsepower requirement of your engine. It also increases how much horsepower you're wasting. Both equate to less MPG and increased engine wear since you're working the engine harder.

If this wasn't true, 60 mph and 70 mph would both require the exact same throttle, and we all know that isn't true.

While you can get better mileage with your specs, your speed makes a bigger difference. For example, going from 1600 to 1400 rpms increases mpg about 3-4% according to an article I read a while back. Going from 70-60 mph will increase it 10-15% easily.