I know you all know I use my ScanGauge II for getting the most MPG's from my vehicles as in the other thread I kept going over here. So here is now the last few trips to McCall, ID now in my 2002 Dodge Cummins... http://g.co/maps/ezxhe

Just filled up tonight 699 miles 35 gallons at 4.19 20 mpg avg. Thats mostly all country road driving 55 and 60 to 65 on the free way. I bit the bullet and bought a scan gauge so Im interested to see if I can improve on my mileage a little.

Here in SC the price is $3.61 the gallon. I'll be checking a 300 mile interstate trip tonight to see what the actual is.Update 335.5 miles on 16.76 gallons = wait for it,,,,,,,,,,,,,, wait for it............ 20.01mpg runnig 70 to 80 mph with 76 mph being a sweet spot according to the lie O meter. Light rolling mounds on I 85 between Spartanburg SC and Charlotte NC. 2 round trips. So I've finally broke the 20mpg barrier just barely LOL, but look how fast I was driving. If I drove like Mike I might be at 25 or 30mpgs

For the last 4 days of working SAR's up on the Sheep Fire I've been buying $50 bucks of fuel every night at $4.299 and so far I just about cleared 1,000 miles of travel.

Hit my best numbers ever today, 18.2 mpg and mosly all in town trips. Will be putting about 175 miles on it mostly hwy this weekend so I hope to see it climb even more. Did I mention I LOVE this NV4500!!

I got my truck to give me 25.4 and 25.6 mpgs (two tank fulls) at 65 mph empty and 16.8 mpg towing my fiver at the same speed (that is until I run out of propane). Propane gives me a consistent 5 mpgs and diesel here in northern Mn is running from $4.399 to $4.639........

Hit my best numbers ever today, 18.2 mpg and mosly all in town trips. Will be putting about 175 miles on it mostly hwy this weekend so I hope to see it climb even more. Did I mention I LOVE this NV4500!!

Report on highway #'s ?

Went to the pull in Wauchula and back, about 170 miles and the rest was around town, even had a few miles with trailer and the parts truck and got 18.3 last fillup.

Just joined this forum yesterday. I've been researching diesel trucks for a month or more and finally pulled the trigger and purchased an 01 QCLB 5 speed, 3.55. Exactly the same color combo as Mikes far as I can tell. I've driven about 2500 miles so far, best was from Buena Vista CO to Boulder at 60-65 25.25 mpg. Last weekend round trip to Taos 900+ miles at 65-70 got 21.4. I have just adjusted the valves today (216K) every one was loose, so maybe I'll get a little better mpg's now. Put in a Smarty at the economy setting, and a Big Filter. Doing the 275 injectors this weekend. Have aspirations of getting 25 at 70mph. Oh yeah, fuel in Taos $4.29, here in Boulder $4.29. Great truck!

Welcome to the forum!Is they 25mpg hand-calculated? That seems quite high :)Sent from my SPH-L710 using Tapatalk 2

Yes, but later I hooked up my GPS and discovered that my ODO is reading 6% higher than the GPS. So actual was 23.8. Now I convert to get actual. Which reminds me...does anyone here have experience in using larger diameter tires to get higher final ratios for better fuel economy? I realize that there is a tradeoff, bigger tires=greater rolling resistance, but also you would get the torque in the sweet spot at a higher actual speed. Thinking of putting some low resistance Michelin 265's on the truck for this reason. Thoughts?

Won't work.

bigger tires=greater rolling resistance

but also you would get the torque in the sweet spot at a higher actual speed

Because by the time you go from 55 to 65 MPH your wind drag doubles and will quadruple by the time you reason 75 MPh so you'll be require to put out even more fuel to over come the speed as well and the rolling resistance, rotational mass, and the increase frontal are wind drag.

The only way to gain serious MPG's would be slam it to the ground (reduced frontal area), use smaller lighter wheels and tire (reduced rotational mass) use a street only tire (reduced rolling resistance), regear to get 1,500 to 1,700 RPM with this combination at 55 MPH (Lowest wind drag).

Go to a tire shop and check out racing slicks. They are super light (next to nothing for rotational mass) and then being there is no tread face (next to nothing for rolling resistance).

Just wanted to update folks on here on what I have done so far to my truck. First I installed an Air Dog Raptor 100 pump with a low fuel pressure switch and LED. Then I put a Smarty in setup for economy. Adjusted valve lash to .009 and .019. All that I already mentioned I think. So last weekend I put some Michelin LTX MS2 265's and the Bosch RV275 injectors. The Cummins seems to be a little more aggressive with these installed. Also I have been playing around with the Smarty, now I have my ODO only 1.04% off the GPS ODO. And this last week I've been running around town smoking people in Level 3! LOL. Last night I replaced the rear diff gear oil with Amsoil. I will probably have to go up to the Northwest this next week so I should have some MPG numbers. One thing I have already noticed is how much better my mileage seems to be with the tires aired up to 70 or so PSI. When they were put on the fronts were only 55, which felt too mushy for me. I haven't read on tire pressures here, but 70 feels good. Guess I need to stay on watching the tread wear to see if that is correct or not. Thanks for all the input on this forum. You guys have been an invaluable resource!

Another way to inflate is do it based on weight.Weight the truck axles and then you can use this formula.(Axle Weight / 2) / Tire Weight Capacity x Tire Max PSI = Inflation pressureFor example my front axle is 4,440 pounds with my 265/75 R16 are rated for 3,415 pounds @ 80 PSI.(4,440 / 2) = 2,220 / 3,415 = 0.65 x 80 = 52 PSI. Another example with 3042# @ 80 PSI (Standard load range E)(4,440 / 2) = 2,220 / 3,042 = 0.72 x 80 = 57 PSI.Or my 235/85 R16 3750# @ 110 PSI (Load Range G's)(4,440 / 2) = 2,220 / 3,750 = 0.59 x 110 = 65 PSI.

Have you played with different settings on your smarty? I actually saw worse #s for mpgs on the economy tune. I generally run sw5 and have it tweaked just slightly and i run consistantly 20 to 21 mpgs. The economy tune is also not recomended for any heavy towing as it has aggressive timing and egts tend to run high when using that tune. Not everyone has the same results the. Biggest factor is HOW you drive. I dont hotrod (well maybe once in a blue moon) but 99% of the time im in economy mode cant afford the fuel and cant afford to fix it when it breaks.

Funny you should bring that up about the Smarty. Yesterday I took a little drive to see how the truck was running before I took off this week and forgot to change the Smarty setting back to 1 from 3, and noticed that the AV MPG on the truck gauge (I know it's wrong but I use for comparison) was higher than on 1. I figured I'd play with the settings on my trip. Also, at my altitude (5300') I would think this truck would need some tweaking to deal with the thin air, but haven't even gone down that road yet! I was reading on here about propane injection, and am I nuts or is this a no brainer for fuel economy?

Dont know how much it could really save you from what ive seen the kits are pretty pricey. By the time you figure that into the cost along with the propane itself...

My grandpa put a propane settup on his 2001 2wd 6 speed and his last trip from Tx to here(FL) he was averaging 23mpg running 70mph with a honda forman 4wheeler in the bed. He just got the cheap $300 kit off of ebay.

Mike, what kind of mileage are you getting when you tow your rv trailer, and how much does it weigh?My camper loaded is around 3,000 lbs and get around 14.1 mpg on back roads running about 60- 62 mph.Thanks.

Back from my trip to Montana and Idaho with some real MPG numbers. Going up to Montana on I-25 and I-90, I got around 17.5 going 75 mph on cruise with negligible wind issues. From Bozeman to Boise going 60-70 on mainly 2 lane highways I got 19.3 no wind. Coming back on I-84 and I-80 with a 2K camper I was fighting a 50 mph crosswind gusting higher and really didn't care about my mileage, just wanted to keep the camper on the truck! This was all on Level 3 with the Smarty. I think if I were going to drive on the 2 lanes more often I would set the Smarty to L1, as on 3 it seems to hunt around a lot more on cruise. FYI what I do when I fill up is go to the surge cutoff, then measure my 2 cycle oil, then slowly top off till I see actual fluid fuel level at the bottom of the fill tube. I doubt I'm off more than a cup of diesel each fillup. I try to fill immediately before driving some distance so I'm burning fuel that might expand if it would sit for a while. I'm really happy with the power and ecomony. Maybe I'll put a turbo back exhaust on sometime, but for the present I'll stay with this. I'm now interested to see what MPG's I get hauling this camper.

My grandpa put a propane settup on his 2001 2wd 6 speed and his last trip from Tx to here(FL) he was averaging 23mpg running 70mph with a honda forman 4wheeler in the bed. He just got the cheap $300 kit off of ebay.

I picked up a 'cheap' regulator (THIS ONE) for $200 and the propane gives me 5 mpg across the board. I now get about 25.5 mpg at 65 mph and towing my fiver I get about 16.5 mpg at 65 mph. Plus it gave me a fair amount more power too!