Your best mileage, class A diesel.

[Dutch Star Don]

What we spend on fuel isn't a huge issue to us, but I do like to get good mileage. I have the Silverleaf program running in my coach and it's been fun to watch the rolling mpg, HP and torque. It took me quite awhile to dial in the Silverleaf program where the fuel mileage was accurate. My wife does the paper and pencil calculations each fill up and I compare it to the computer. In a 40 gallon fill up, we're usually within a 1/2 gallon or less of each other. I also drop a jack and level the coach from side to side when I fill.

With that said, our coach since new has been getting 8.3 mpg overall. In the last two years, I retired, slowed down, added a Source Engineering engine fan (rear radiator) and on our last trip I added a DigiCR computer chip. The engine fan was very impressive and gave seat of the pants performance. The chip is hard to notice, but fuel mileage picked up.

Last Friday we drove from Los Angeles to St George Utah. Our coach is a 36' DP with a 400 ISL. We weigh in at about 32000 pounds. On this trip we were towing my 4 door Silverado with our RZR in the bed for a total of 7300 pounds. I set the cruise at 60 mph for the trip. When we arrived in St George we took 43.7 gallons and got 9.3 mpg.

After we stopped for the evening, we got a call from our daughter who had been hospitalized with a bad gall bladder. We drove straight home the next day and the coach took 43.3 gallons.

To help mileage, (when traffic permits) I don't race up on ramps and I slow in advance (coast) of exiting. I don't like the feel of my throttle so most of my driving is done with my SmartWheel cruise control. When I accelerate up an on ramp, I set the cruise as soon as I hit 45-50 mph and then just keep hitting the cruise control every couple of seconds until I reach 60.

Lastly, I use a diesel additive (Opti-Lube) for better fuel lubricity. So in the last year or so I've been getting low to mid 9's towing and low 10's not towing. My lifetime mpg has increased now to 8.5. We also hit 6000 gallons of fuel used on the last trip.

With the SIlverleaf program, you can see that speed is the biggest mileage killer. Even in strong winds, I can back off the throttle a couple of mph and see my mileage not take a huge hit.

[calhyatt]

Originally Posted by Winepress

Move on folks, nothing to see here. Someone missed their meds, all is OK, move along now.

Time to close this thread. No reason for folks to get so upset over a simple mistake made by the OP. The intent was good but this has degraded to a point that defeats the purpose of our open discussions on this forum. Just my opinion..

[mel s]

Originally Posted by calhyatt

Time to close this thread. No reason for folks to get so upset over a simple mistake made by the OP. The intent was good but this has degraded to a point that defeats the purpose of our open discussions on this forum. Just my opinion..

I agree!
Mel

[rssnape]

Originally Posted by bobioknight

Ok so let me begin by saying I absolutely did not get 17mpg. However this is what I did experience on this trip. I fueled up when arriving back in town after a day at the mechanic installing new tires and checking the air leveling system, I topped off the tank with as much fuel as possible because I totally expected that I would have to fuel up a second time during our trip and wanted to get as far as possible. We left for Napa leaving early in the morning, we headed out and travelled non stop to our destination. Traveling at 55 most of the trip except the few times I caught myself gaining speed. I did not use speed control but was in economy mode. And did hang out behind trucks for most of the trip mainly to help keep my speed consistent and act as a wind break. The new michelin tires 255/80 22.5's all were aired up to between 105 and 110 lbs (quite a bit more that was necessary for my weight). the weather was pretty overcast so it stayed cool the entire trip so I did not run air conditioning. I did run the generator about an hour during the trip to keep the batteries up since we did not have hookups where we were parked. During our non stop trip back to the house I noticed coming back on the 5, I only had to use light pressure on the excellerator and the fuel needle barely moved, I surprisedly had barely used 1/2 the tank and we were getting closer to home, most of the fuel was used when hitting stop and go traffic near magic mountain, up to the 91 and cleared up at the 15 which is about a half hour from home. I returned to the fueling station, (same one I filled up at, and it was the same exact pump) I leveled, and pumped fuel til it was topped off at 65.x gallons. (I think my tank hold 100 to 110 gallons). I checked my odometer which read 1120 miles (this was wrong so calm down) after understanding that 17 mpg was utterly rediculous I went back to google maps which indicated my trip should have been 952 miles, so I retraces my route using my gps navigator and came up with 960 miles.

I never would have let the guage go below 1/4 tank, yet come to think about it, I was probably pretty silly to trust a fuel guage that did not move much during our return, I kept expecting it to take a long time to hit a certain point the drop rapidly like it does in my truck. But it just slowly dropped somewhere between 1/2 and 1/4 tank and we were very close to home, So I never got nervous about running too low.

So to sum up, 960 ONE stop miles, 55mph, max inflated new tires, some stop and go traffic, 1 hour on the generator, topping off fuel coming and going (yes I have pumped fuel before), waxed and polished full paint, low profile body, full 110 gallons of fresh water, black and gray tanks empty, couple hundred pounds of camping stuff in the storage area, 3 adults, 2 kids. Beer, wine, pop and food in the frig, dual roof air units, sun roof, satelite, 4 antennas, couple roof vents, Alcoa rims, 1993 country coach, magna, 300hp cummins, 5 speed allison, and one flux capacitor (80's reference, and joking) Not towing anything nor do I have any special exhaust or equipment.

I might add that when twist the headlight pull know to turn my dash lights on and off, the guages do fluxuate higher and lower depending if the dash light are on or off, so I do know my guages can be off a bit.

This coach is new to me so I am not sure of all the systems, but I do know how to pump gas, use a calculator and obviously pick a good Motorhome. Have fun.

Reading your specifics I would bet your better than normal mileage was based on your tire pressure and speed. You must have a steady throttle foot as well as you mentioned not using cruise. Happy travels!

[Ramzfan]

Just to chime in...I just returned from a 6,500 mile trip to So. Carolina and other places. For the total trip, I got 7.75 MPG on my Meridian 36G with a CAT 350 towing a Jeep Grand Cherokee. I do my own calculations (don't trust that little screen that I have to get down on my knees to see) and I kept track of everything! Not as good as I would have hoped, but like several have commented...who cares? I had a great time!

[chuydog]

'04 CC Inspire with ISC getting a solid 8.3 to 9.0 @1600-1650 RPM and sticking close to 60 to 65 MPH.

Using calculator and common sense, I think.

[AGP]

My average mpg is 9.5 as read from chassis data port via silver leaf. Mileage to date approx 13,500, individual trips vary from 8.4 to 10.8 depending on conditions such as towing or not, wind, etc.

[srh]

Originally Posted by Ramzfan

Just to chime in...I just returned from a 6,500 mile trip to So. Carolina and other places. For the total trip, I got 7.75 MPG on my Meridian 36G with a CAT 350 towing a Jeep Grand Cherokee. I do my own calculations (don't trust that little screen that I have to get down on my knees to see) and I kept track of everything! Not as good as I would have hoped, but like several have commented...who cares? I had a great time!

That is about right! I had 2006 Phaeton with the CAT 350 and that is what I was getting! Happy and safe travels!

[UltraKen]

Originally Posted by LakeKerrGuy

I participated in and followed the thread where you reported getting 17+ mpg. I'm glad to see you are still here and cannot wait for your next trip report. Call me a cynic or skeptic but I still believe something is wrong with your mileage report.

I once got really great mileage in the mountains of Virginia. Instantaneous reading on my VMSpc of 255mpg - costing downhill for several miles.






Under more normal conditions I get between 7.7 and 8.5mpg on a daily trip basis. Overall is 8.2 for the life of the coach *~71K miles according to the VMS. See bottom line "KNW"

[UltraKen]

Originally Posted by mel stuplich

That is a great question.
Just like your reported 17+ MPG, I believe you will find that your quoted figure, "9 mpg (national average)", is a bit high for class A diesels.
I'm looking forward to your average of the MPG figures of those who reply.

BTW, the average of the 8 posts so far, including my 8.5 is 8.51875 MPG, (however if your 17 mpg were included the average jumps to 9.46).

Mel
'96 Safari, 250hp 3126 Cat,
(8.5 MPG overall average)

Mel:

Our Identical coaches, except for the hp, are very close in mpg. You carry more tools, we have the wine cellar.

[UltraKen]

Originally Posted by bobioknight

Ok so let me begin by saying I absolutely did not get 17mpg. However this is what I did experience on this trip. I fueled up when arriving back in town after a day at the mechanic installing new tires and checking the air leveling system, I topped off the tank with as much fuel as possible because I totally expected that I would have to fuel up a second time during our trip and wanted to get as far as possible. We left for Napa leaving early in the morning, we headed out and travelled non stop to our destination. Traveling at 55 most of the trip except the few times I caught myself gaining speed. I did not use speed control but was in economy mode. And did hang out behind trucks for most of the trip mainly to help keep my speed consistent and act as a wind break. The new michelin tires 255/80 22.5's all were aired up to between 105 and 110 lbs (quite a bit more that was necessary for my weight). the weather was pretty overcast so it stayed cool the entire trip so I did not run air conditioning. I did run the generator about an hour during the trip to keep the batteries up since we did not have hookups where we were parked. During our non stop trip back to the house I noticed coming back on the 5, I only had to use light pressure on the excellerator and the fuel needle barely moved, I surprisedly had barely used 1/2 the tank and we were getting closer to home, most of the fuel was used when hitting stop and go traffic near magic mountain, up to the 91 and cleared up at the 15 which is about a half hour from home. I returned to the fueling station, (same one I filled up at, and it was the same exact pump) I leveled, and pumped fuel til it was topped off at 65.x gallons. (I think my tank hold 100 to 110 gallons). I checked my odometer which read 1120 miles (this was wrong so calm down) after understanding that 17 mpg was utterly rediculous I went back to google maps which indicated my trip should have been 952 miles, so I retraces my route using my gps navigator and came up with 960 miles.

I never would have let the guage go below 1/4 tank, yet come to think about it, I was probably pretty silly to trust a fuel guage that did not move much during our return, I kept expecting it to take a long time to hit a certain point the drop rapidly like it does in my truck. But it just slowly dropped somewhere between 1/2 and 1/4 tank and we were very close to home, So I never got nervous about running too low.

So to sum up, 960 ONE stop miles, 55mph, max inflated new tires, some stop and go traffic, 1 hour on the generator, topping off fuel coming and going (yes I have pumped fuel before), waxed and polished full paint, low profile body, full 110 gallons of fresh water, black and gray tanks empty, couple hundred pounds of camping stuff in the storage area, 3 adults, 2 kids. Beer, wine, pop and food in the frig, dual roof air units, sun roof, satelite, 4 antennas, couple roof vents, Alcoa rims, 1993 country coach, magna, 300hp cummins, 5 speed allison, and one flux capacitor (80's reference, and joking) Not towing anything nor do I have any special exhaust or equipment.

I might add that when twist the headlight pull know to turn my dash lights on and off, the guages do fluxuate higher and lower depending if the dash light are on or off, so I do know my guages can be off a bit.

This coach is new to me so I am not sure of all the systems, but I do know how to pump gas, use a calculator and obviously pick a good Motorhome. Have fun.

Well, that explains it. You had fresh Dilithium crystals.




BTW,

[deandec]

67000 mile average. Hand calculated. Adjusted for odometer error factor. Adjusted for generator use.

7.3 MPG

31000 lb coach. 5000 lb car. 300hp Cummins 8.3L with 4.8 rear end ratio.

[UltraKen]

Originally Posted by greatlakes

Yes I agree that I would not ness put all stock on the GPS figures as they may not be able to account for the added distance from change in elevation. I'm not 100% on that but I would think close enough.
My RV had a recall to change the tires from 175 to 195s due to weight but I don't believe they adjusted the Speedo to account for the larger tires. Seems to be off about 7mph around 60. So my mpg is prob not as good as what I calculate due to the millage is prob more than what the odometer is saying.

If you remember the previous brand tire you can look them both up on the manufacturers' spec tables and find the Revolutions per mile. Those two numbers will give you the simple %difference and the amount of adjustment required, Personally I wouldn't bother with it unless the discrepancy is more than about 2%.

[Sutler]

Me and wife get about 8.5 to 9.5 out of our 330 cat if I keep it at about 60 to 65 mph.Were happy with that have all the power we need.