OK Gang, I've been tracking my mileage since I picked up my LLY on June 5th. Here's what I track and calculate for each tank. The light blue columns are what I enter, the while cells are calculations.


http://www.dieselplace.com/forum/uploads/D51_log1.gif


I found something very insteresting when I graph the MPG and Average MPH on the same page. It seems as Average MPH increases so does the MPG. Does that seem odd to anyone?


Here's the graph.


http://www.dieselplace.com/forum/uploads/CD2_graph1.gif





Anyone got any thoughts on this trend? And is anyone else seeing anything similar?

Makes sense. MPG climbs, eventually the average will climb with it. The graph shown make total and complete sense.





Bill

I think you've misunderstood. This is average MPH on the tank charted with MPG.


So, on 7/30, I filled up. 373 miles on the tank, 8.1 hours, 23.062 gallons to fill it.


373 miles over 8.1 hours = average speed of 46 MPH.


373 miles filled up with 23.062 gallons = 16.17 MPG.


I find it's interesting that as my average speed per tank increases so does my mileage. theoretically, you would think the slower you go, the better mileage you would get.


I realize there's only 12 data points here, but it looks like the faster I go, the better the mileage.

As your avg MPH increases so will your MPG, I think it will keep going up until your avg MPH goes past a certain.


For instance if you could possibly get your avg MPH beyond 62 MPH you would probably start to see the inverse and the MPG will start to drop.

It makes perfect sense up to a certain point. If your MPH increases, that means you probably have a higher percentage of highway miles. You will reach a point of diminishing returns when drag overcomes the benefit of speed and momentum.


Kind of like what Grabs said.

totally agree with that - i keep track of mine as well and it will have a steady climb up to about 65mph, after that it wont unless its very easy driving, no hills and have cruise set at 70-75

It makes perfect sense.....baimpala explains it well...its all about efficeny.

Instead of speed, drag and momentum it is probably the effect of stopping and starting while going through town/city that is lowering your fuel mileage and lowering your average speed through stopping and starting.

trapman,


You're absolutely correct. I should have said that "at speed, drag will overcome the effects of speed and momentum to bring down the mileage." This effect will occur on different vehicles at different speeds. A very low drag coefficient car will not experience a lowering of fuel economy until a much higher speed, whereas a brick powered by a duramax will see it at much lower speeds.


Thanks for the clarification. . .
Dennis

heh - well this is good to know. All the more reason to push that pedal down a little farther when I'm on the freeway.


FWIW, this will be my first full tank with the Edge/Attitude installed - I'm really interested to see how that's going to change my results.

heh - well this is good to know. All the more reason to push that pedal down a little farther when I'm on the freeway.


FWIW, this will be my first full tank with the Edge/Attitude installed - I'm really interested to see how that's going to change my results.





First mileage check with the Edge on huh? I suspect your experience will be similar to mine and others I've seen posted here.


That is a drop in MPG, especially the first tank...http://www.dieselplace.com/forum/smileys/HiHi.gif

All my trucks get better fuel mileage with the Juice. Of course thats only when I'm not spinning the tires, or racing at the dragstrip, or street racing, or just showing off, etc., etc., etc.

Energy is work over time. Your milage will be based on what gear you are in and how efficient your engine is running. The Duramax is very efficient. If you look at the horspower curve, it rises until 3000 RPM. Efficiency is only one piece. Drag goes up by the square of velocity. The horsepower curve probably comes close canceling out the drag. I have watched my instant economy and noticed that in 5th the mpg goes up as I speed up, but as I hit a hill or headwind, it goes down. If we had a flat road with no wind, we could test this by driving 2 different speeds across the same stretch and measure the milage at speed with the DIC.