With my old truck(3406E CAT), my ECM numbers, and "at the pump" were about 0.7-1mpg different. ECM showed better mpg.
My current Acert ECM, and "at the pump", is just about the same.

Anyway, i watch my mpg every fill up, "at the pump"!

From a recent article on fuel economy in the Canadian trucking magazine, "Highway Star" ("There's No Silver Bullet", by Jim Park)

"...Jim Booth ... is a former test pilot for Caterpillar, and a zealot when it comes to fuel economy. He's retired from test service with Cat, and now hauls freight for Cat between northern Wisconsin and Peoria, IL. He manages 9.3 mpg consistently our of a C13 Cat.

His style is to step so easily on the pedal that you'd swear it was made of crystal. Most would call his accelaration painfully slow, and his adherence to 55 mph nearly unbearable, but you can't argue with 9.3 mpg."

I hate to be a fly in the ointment...but as a stickler for technical accuracy...
wind resistance does not go up "exponentially"...
wind resistance is proportional to the square of the velocity...

simply put...double your speed=> four times the wind resistance...

so...55mph vs. 70 mph will yield a 61% felt increase in wind resistance.

Still substantial and worthy of consideration...but not nearly "exponential".

IIRC, anything "to the power of two" or "squared" is an exponent.

Columbia is not a bad truck, i own one with Detroit 475, dont let the lower price fool you, thats a good truck that a'lot of my friends have had for years...

And who said a higher education doesn't help in trucking.....Watch out, the techies are taking over!!!

What you said right there, is what exponential means.

I don't know what "IIRC" means.....but:

to the power of two means it varies as the square of the variable...
the two is the exponent and it is fixed....it is only correct to say it varies with the square...(it could be cube or fourth or fifth power etc but the exponent is fixed......)

in order to vary "exponentially" the varible would have to be the exponent with a fixed (or variable) base.....

e.g.: IF resistance 'R' varied "exponentially" with velocity 'v' and constant 'K' as the base the equation might be:

R=K to the power v (I do not know how to express a superscript here)

thus...if you double the v
R=K to the power 2v and you have effectively SQUARED the R
BUT>>>>if you triple the v
R=K to the power 3v and you have effectively CUBED the R
and so on with greater increases....

an "exponential" function increases at a much greater rate than a simple square function....
but do not lose the salient point here.....a simple increase in speed does not just give you an equivalent increase in wind resistance (and presumable decrease in fuel economy)....it goes up much more quickly!!

I do not want to be argumentative (even though I am) but specificity and accuracy are important...

Here endeth the lesson.... (until next time!!!)

If I remember Correctly, it means, If I remember correctly. :D

Yet again, another reason to lighten up on that right foot!

I beg to differ. Not in this case. I'm sure the original statement was understood by all. :roll: