While driving along on my way to POG2, I started thinking about a way to impress my good friend Brian ( owner of an 8V92) with the fuel economy of my Series 60. We both have a ProDriver installed, and it shows the average fuel economy obtained since the last reset.

My curiosity was really, how high could the fuel economy go in a completely best case situation? It seems to me that this would be just driving along at a steady speed, no wind, no hills, always in the highest gear of the transmission. Well, of course a higher number would be obtained if going down hill with a tailwind, but that would not be realistic.

I live in Washington State, and it seems that no matter where we go, the road has hills. In regular driving, with traffic, various accelerations and decellerations, over the course of a tank of diesel, I usually average right around 7.5 MPG. That is my 45 foot Marathon, loaded with everything we use, and towing a VW Golf at 2500 pounds.

So, I filled up the tank in Winnemucca, NV, reset the Pro Driver, hopped on I-80 and set the cruise control on 55 mph, and let the traffic roll past ( the speed limit was 75!). I did this for 80 miles and watched the fuel economy average creep up until it got to 9.32 mph! There were a few hills, but not much wind. It was a real world situation. I am amazed that the economy is this high considering we have a house going over the road.

I took a picture of the display at 9.25 mph and emailed it to Brian with a link to one of those magnetic fuel conditioner websites, and told him how good it was working.....he did not bite.

Anyway, I think that gives a kind of upper limit on the efficiency of operating the coach. On the way home, I did it some more at different speeds to see how the faster you go burns more diesel.

95 miles at 62 mph in Oregon yielded 8.71 mpg, no headwind.

65 miles on I-84 with a 7 mph headwind in Northern Utah at 65 ,mph yielded 7.45 mpg. There was one big pass.

92 miles at 66 mph near Boise yielded 7.6 mpg, 5 mph headwind


136 miles at 71 mph on I-85 in southern Idaho yielded 7.13 mpg. 8 mph headwind.


Conclusion:

At $3.00 a gallon, you can minimize operating cost by driving 55 mph, and you will pay 33 cents a mile, or if you hustle at 71 mph, you will pay 42 cents a mile. A 1000 mile trip would cost $90 more at the higher speed.

My idea was just to put this all in perspective. Your thoughts and comments are always welcome.