MPG VS. SPEED

[WingmanIII]

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.

[solo379]

Over a 5 day long run it will take me another 5 hours of driving

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:

[Ian Williams]

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.

[flood]

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

[solo379]

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.

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 , 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:

[tracer]

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

[merrick4]

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.

[person]

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

[PhuzzyGnu]

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.

[allan5oh]

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

$3 a gallon fuel changes everything.

[solo379]

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:

[WingmanIII]

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

[BanditsCousin]

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:

[allan5oh]

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

[Ian Williams]

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.

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.

[Longsnowsm]

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

[allan5oh]

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.

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.

[PackRatTDI]

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.