MPG!!! Mine came with that option

[billnourse]

Went to Denver over the weekend to see my brand new grandson and this was the first time I really had the chance to check the D/A for milage on a long trip.
First tank: 20.4 MPG- 55-60 MPH for Deer and Elk herds, 65-75 the rest of the time. Had to go over two little hills(10,800 and 9,400 ft.)

Second tank: 17.4 MPG this included town driving and 75 MPH interstate with a 40 MPH head wind.

Third tank: 21.6 MPG 60-70 MPH with those little hills again.

Even in the mountains I experienced no busy shifting, and the downshifting going down grade was a plus.

Bill

[Nels]

Congratulations on the new grandson!

Your mileage compares well with mine.

[pullinpower]

Mine has never gotten near 20mpg :mad: you got a good one billnourse.

[Alli-max]

:mad:
Straight interstate with mine (yes, 100% interstate) is ~16.5 at 70 - 75 MPH!!!!! computer updates, K&N, swiss cheese airbox, and Kennedy Exhaust are the only mods.

I just DO NOT understand. And no, its not the bumper MDrag.. :D :rolleyes:

[RustyRoss]

Same here. Best ever is 17.2 :mad:

[ndamico]

Here is my MPG report. with just over 2000 miles on the truck, I drove from Sacramento to Lake Tahoe and back over the weekend. Traveled from sea level to 7000 feet and back down, crusing about 85 most of the way. MPG for the trip was 17.25. I seem to get closer to 15 or 16 driving around town, but we have a lot of traffic here in sacramento, and my longest stretch without stopping is probably half a mile..then again i do have a lead foot. overall i'm satisfied, considering my old 1/2 ton gasser got about 11 or 12...and it wasn't near as fast!

[bandit]

My milage has been fairly consistant. In warm weather around town, 15 to 17. On the road (been making 350 mile trip twice a week since January)milage will run from 16 (raining with strong head wind) all the way up to 20.6! Most times on the road will get high 18's to high 19's. The only major difference I have noticed seems to be between winter and summer. Dont think we get blended fuel here in Arkansas so it must just be ambient temp.

[TXDMAX]

I dove back from Houston last week-end averaging 75-85 got 17-18 mpg. Little disappointed but I know I was cruising pretty good. I get around 15-16 in town and have 22k miles on her.

[TXMAX]

Empty:
17.1 average around town.
19.8 highest at 65-70 mph
17.9 last weekend going to College Station and just flying at over 80 for a good part of the trip.
Towing:
4k, boat only 14-15.5 at 70 mph
7.5k 5vr with 4k boat 8.58 mpg on the way out and 10.49 on the way home (it learned?)

Overall, happy as a pig in it. My PSD never got 17 on its best day.

Abe

[Carli_max]

I just got back from Myrtle Beach, and my avg. MPG was 18.1. That was taking the time to fill the tank to the neck where I could see the fuel each time. It was all highway driving 75-78 mph. I'm wondering if the guys getting in the 20-21 mpg range are truly filling their tanks up so they can see the fuel in the neck?? I can put another 1.5 gal in after the first foaming! On the other end of the spectrum, I wonder if the guys getting 15-16 mpg have larger tires, and are compensating for the increased diameter of their tires?? I have 265's which I figure are 3.75% larger than the 245's that the truck is programmed for!! Just wondering if we are all comparing apples to apples??

[James S]

Hi Folks,

The difference between the 245's and the 265 is eight percent. 245 times 1.08 equals 264.6. For those with Canadian trucks converting your milage to the canadian gallon, instead of just multiplying your milage by 1.2, if you have 265 tires, multiply it by 1.28, to get a more precise mile per gallon reading, ASSUMING your speedometer has not been reprogrammed. If it has, just multiply your milage by 1.2 to convert from the 3.78 litre American gallon, to the 4.55 litre Canadian gallon. That's my two cents worth.

James

[01_Duramax_Dually]

Man...I hate to muddy up the water,
I have gotten 21.9mpg best going 55-58 MPH with cruise on, flat land, Interstate 5. Typically average 16.5-17 65-70

Most amazingly, I have the 3500, 4x4 CC Long Bed BUS.....

Dailey driving is still 15-16 depending on how hard I drive and traffic.

Towing is 11-12 but that's just because I go 80...... :D

Oh and I have No mods other than drilled Air Box.

Regards

Jeff

[JF]

24,677 miles and average is 17.9 MPG I've tracked every fill-up. Would like to see a little more.

[MohawkMax]

Here's mine for the first 2 months
277.8 15.864 17.5
299.9 17.69 16.9
100.8 5.94 16.9
289.5 18.27 15.8
284.1 17.34 16.3
297.7 16.99 17.5
175.7 9.93 17.6
286.6 17.2 16.6
150.7 9.29 16.2
354.3 21.61 16.3
316.1 18.056 17.5
360.6 20.289 17.7
329.9 17.821 18.5
327.6 18.117 18.0

Mostly driving to work 22 miles one way 55 to 65 mph. Getting better all the while .I'm Happy!

[James S]

MohawkMax, you need to please explain those numbers.

[stevej]

Only have 800 miles on the truck, 300 mile I5 trip at slow 60 mph average gave 20 mpg, day to day commute 32 miles round trip half stop and go getting 16 mpg so far.
The fill up is important I can get a 3 gallon varation in the pump kicking out and top off depending how far in I jam the nozzle. If you let the station attendent (we still have those in Oregon) do the fill you'll never be able to calculate trip mileage accurately.
Happy as a clam, amazing that somthing this big with the power it has can do this type of MPG.

sj

[NutNbutGMC]

^.... Mohawk's numbers; Miles / gallons / MPG

[dmaxster]

hey nels long time since we last talked......hope the truck is doing great......picked truck up on Sept. 24th 2001 and first tank I got 19.2 MPG the best it's had....now have 20475 on it and average 17.9 MPG and log every fill up and file on spreadsheet......very happy with this rig, the best decision I have ever made.....thanks dmaxster :cool:

[MohawkMax]

NutNButGMC

Thanks, they don't call me a newbie for nothing.
There was space between the numbers when I posted.

[NutNbutGMC]

^...There still is a space between the numbers. Not a problem... Welcome to the forum. Don't let that MPG thing get you in a panic. It's only diesel. :D :D Again, welcome to the forum. smile.gif

[tysmith]

Ran into a guy today who filled up yesterday with 45 gal - he has 3500 with aux tank - and today his fuel gauge read E and his fuel light was on. :eek: That's the worst mileage ever!!!

Think he has a sender problem?

[AB_DURAMAX]

What am I doing wrong....I have been only getting 12-13 mpg solo the last couple of months. No changes to the truck other than the updates.

[Carli_max]

James S,
I need to question your math with regards to 245's and 265's. Wouldn't you need the diameter of the tire * pi (3.14)to get the circumfrance. Then you can compare the rolling distance of each size. When I did the math I got 3.75% more for 265's to 245's. I then took my raw mileage and multiplied it by 1.0375 to get my actual mileage!! Any comments from the tire & math experts out there? ;)

[MACGMC]

Haven't gotten better than 16.5 on highway since new 2/02, getting only 13.5 in town, Even using additives. Recently pulled 14k 5th wheel to SanFrancisco and back averaged 8.5 towing around 80, at sea level got 12 on 1 tank. Runs great at sea level, Still only 8K on truck.

2002 GMC SLT/ CC/SB 4X4

[klthompson]

Good day guys.

Well, I posted this info in another thread, but will throw it in here as well. I'm afraid I'm gonna be the odd man out with these numbers.

For all the numbers reported, I am unloaded (less than 700 lbs in the bed), with a tonneau cover. Always fill until I can see the fuel in the neck.

My calculations were (kilometers traveled)/(liters of gas at fill up) * 2.35( conversion to US MPG) * 1.2 (conversion to CDN MPG) * 1.08 (accounting for 265 michelins)

During the winter, I was getting 19-20 US mpg (22.5 - 24 CDN mpg) doing approx 115 km/hr highway, or 17-18 US mpg (20-21.5 CDN mpg) 50/50 highway/city.

This last week, decided to slow it down a bit and drive 100 km/hr highway on a trip, may be a little under. Got 22.5 US mpg (27 CDN mpg!) average on two tanks. May be they switched to summer diesel at the same time? I dunno, but I do know that I love this truck!

Take care all!

- Kevin -

[Greg Watkins]

I guess I get to muddy the waters also. 2k2 2500 CC 4x4. Stock tires. I have only 2300 miles on the truck. I have averaged 16.97 mpg since new. This includes towing a 7k travel trailer for 275 miles. HIgh is 19.5. Low is 13.2 while towing. I can't complain at all. The 2k Suburban with the 5.3 doesn't do this well ESPECIALLY while towing smile.gif

Here are the numbers. I DON'T have any mods at all yet. I DO fill up the gas tank until the fuel is right up to the neck.

miles/gallons/mpg

387.5/20/19.3
310.1/17.5/17.72
97.5/6/16.25 (towed a utility trailer @75 miles)
274/14/19.5
178.9/10/17.89
290.8/21.2/13.7 (towing)
229.7/12.6/18.2
225.7/17/13.2 (towing)

greg

[DSLPOWR]

Ehhh, some of you guys are lucky. MPG still seems to be all over the board. I get better averages with my 3500 loaded than I do my 2500HD empty. :mad: Had the updates done "once again" and it seemed to give me another mile or two but thats it. They checked all the perimeters with tech II and everything is in check, I give up, still love the truck though! :D

[mackey_62]

Looks like I'm still in the middle here for MPG.
First tank about 16 mpg. About 8 tanks later I'm up to about 17.5 mpg. Went about 500 mi. last weekend round trip to Niagra Falls, 74mph on Interstate. Disappointed when I got home and figured about 18.8
Was really hoping for one of those 21 mpg's I've been seeing here. I also take my time fillin her up, leave about a cup on the ground to be sure.
Hoping for supply of winter mix to dry up here in Central NY, can only get better!
About the 245's vs. 265's: Also think the difference is only about 3-4%, can't remember the exact number I calculated.
Found a website awhile back to compare tire sizes. Pretty handy for us math impaired.

Tire Size Calculator:
www.miata.net/garage/tirecalc.html

[bluenote]

The key for breaking 20mpg, at least with my truck, seems to be keeping those rpm's at 2K or under. Before I had my tonneau cover, I could break 20mpg only if I stayed in the 60mph range, but now I can get that mileage at up to 70mph. Also, after about 10-11K miles, the economy and performance seemed to pick up some. My daily driving is generally around the 17mpg range, but that includes a decent amount of city miles, and I like to drop the hammer occasionally on take-off. :D

[rberner]

Getting 18 to 19.5. Doesn't seem to make a whole lot of difference whether I'm in town or on the road. Have the 6sp. As I put miles on it, it is getting better. Usually drive 75 to 80 on the road. Tried to stay under 2000 rpms once and didn't see any difference at all.

[walkerkd]

thats about right with my 2001 i get about 20-21 but its so hard to keep my foot out of it hahah.. just here in ft worth from the house to work 30 miles i filled up yesterday i was getting 19.5 or better city, highway, playing catch my pstroke catch me!!! hahah!!!

[Mike Colville]

Mine reads 10% off ie. im really going 77 when it says 70. I just drove 100 miles on the interstate and compared it to the mile markers. Also calculated it using the time it took between milemarks. Im runnin 255-85-16's....getting 18-19 with the new treads, although I still drive the same speed (on the odometer, that is!) Set her at 2000 rpm and go. :D

[hoot]

I'm also running the 255/85's but everytime I drive by one of those radar trailers that display my speed, it's almost exact to my speedo. Maybe my speedo was showing 5 or so less, stock.

[AlaskaDmax]

Hoot,

The cops around here set those radar signs up to be about 5mph off....which side off I do not know...I think that if it says I am going 25mph my speedo says 30mph....and this is with different vehicles.

[TBC]

We are all pretty close on mileage. The temp, terrain, driving habits and conditions all contribute. I think we are being pretty honest. I have heard some pretty rediculous mpg from the D****e boys. The F**d boys don't talk about it to much. I think we are doing well considering the power. We are all probably pretty heavy on the pedal. This truck just makes you want to push it hard. The guys that seem to be on low end need to check tire pressures and driving habits and conditions and also consider how much idiling you are doing. My mileage will vary a good deal.

With just pure highway driving I really believe the mileage is in the mid 20's but as soon as you start throwing in city driving it pulls the average down pretty quick.

I STILL LOVE IT.

[DogDays]

Don't know how scientific this was. Had to take trip to Phoenix last week. Day before trip I had oil change done, replaced fuel filter, replaced tranny filter and new air filter. Always fill up to where I can see fuel in neck of the filler. I live right down on the border and it's 225 miles to Phoenix for me. Stopped on way back home where fuel was cheaper. Was running at 24.2 mpg (maybe my lucky day). Running empty 90% of the way on I-10 between 65-75, flat road. Maybe it was changing the all those filters the day before, normally get 19-21 running to/from work during week, also flat road. Currently at 13,250 miles and seems to be getting better every day. :rolleyes: :rolleyes:

[bora]

Truck has 1180 miles on it. My city mileage is
around 14 or so. Strange thing is that the mileage is improving a lot as I get more miles on the truck.

My first tank was at 14, then it jumped to 14.5, then to 15.5 and my last tank was at 16.5.

I can't wait to take the truck on a road trip and see what I get.

[Idle_Chatter]

bora, I'm seeing the same thing. My in-town mileage has been going up for the last month. I drive about 65-70 miles commute each day, lots of stoplights and rolling suburban Pennsylvania two-lane hills. Max speed in short stretches is 55 and my GPS shows an average speed of 40 or less each way. My mileage used to be in the 18-19 mpg range on the interstate and more like 16-17 in-town and stop and go. Well, I've been "drivin' it like I stole it" hotfooting it off the stoplights and my last three tanks were 19.4, 19.6 and 20.1!! I'm lovin' that, cause diesel up here in MD/DE/PA is from $1.34 to $1.48 a gallon! :D

[dmaxster]

Hi Tom,
Long time no see or should I say haven't heard from you in awhile....where have you been.? so when did you go to Penn. and what you've been workin on..?

Well guys, I have been pulling the old race car around....the trailer with only some of the goods in, is weighing in at 15,000 and the truck is weighing in at 7500 so I am towing 22500.....We were pulling in Wausau and all I can say is the tuck did very well. it's kinda hilly so alot of down shifting and the Allison worked great.....this trailer is not a match for the old Duramax and the Allison....any guy who has an Allison in charge will never be let down...Right???? the only bad thing I can say is the fuel mileage.....It was really windy so I am taking that into account and I guess it's not really bad but did take me by surprise....180 miles to a tank of fuel....I have a short box so I don't have that much fuel to start with.....I averaged 9.5 to 10 mpg's......it's not really that bad but like I said it took me by surprise.....Right now at this time I wouldn't give up my dmax for nothing......I like the way the Allison works and the power of the Duramax......I thank the General for such a well equipt. truck......Right now my truck has 23500 on it....I am averaging 19-20 hwy and 17-18 cty...so with an emmpty load I can not knock the fuel mileage.....it seems since I started to tow that my truck does seem to have more power than it had.......sorry for such a long winded post........dmaxster

I had posted this on a different topic and had though you may want to know...

Tom fuel around here is 1.399 and average some places are 1.42 or even 1.45.....Went to Indiana a week ago and paid 1.19 down there....I was in heaven.....so nice to here from again....dmaxster
:cool:

[KompressorMan]

The first 15,000 miles and all I could get was 15.5 to 16.5. Now with 26,000 on it and I'm up to 19.3 with me driving at about 75 on the interstate. With my wife driving it drops a couple of notches. Her philosophy is damn that pilot injection, let's hear her rip!!!

[Idle_Chatter]

Hey, Maxster! Doing good, but working my tail off. I was out of work in Wisconsin from Dec. 7th until I headed home to Florida mid-Feb. I interviewed for a job I didn't get in North Carolina and then I came up here to MD/DE/PA on a contract job March 11th. I'm living in Elkton, MD - working in Kennett Square, PA. I'm working out of the Exelon Nuclear Mid-Atlantic regional office and commuting to and from the four nuclear sites in the Mid-Atlantic: Peach Bottom, Three Mile Island, Limerick and Oyster Creek. Been working 10 and 12 hour days and not doing much else. Been just feeding the Max fuel and changing the oil and driving it every day. It's been getting better and better - I can't get over the increasing fuel mileage lately! I just updated the spreadsheet in my link - I've got 22,250 miles on it and not a single problem other than that damn drippy Amsoil dual remote connection! I'm about to yank that sucker off there and put on a standard filter until I can get a solid block machined for the hose connections to the filter housing. I'm afraid to overtighten that two-piece cast potmetal adapter and risk a blowout and loss of oil pressure on the fly. As it is now, I lose about a pint of oil every 800 miles and my undercarriage is permanently rustproofed! tongue.gif

[Nels]

Dmaxter, 'chatter, glad to hear from you again! I was driving in the PA hills a few weeks ago. It's a blast with this truck! I got 20.5 and 20.4 mpg on two successive tanks on that trip. The mileage has been trending upward lately. The warmer weather has something to do with it, but I'm getting better mpg now than I was last summer. It has 17,000 miles on it now and seems to get better and better as the miles rack up.

[DetroitBob]

Here are some tire specs gleaned from a Cooper Products Manual for comparison.
Tire Dia Rev/Mile Loaded radius
245/75R16 30.44 680 14.20
265/75R16 31.54 654 14.70

245/75R16 30.44 680 14.20
265/75R16 31.60 654 14.70

I wonder how the tire speed affects the diameter. Does it grow as the dragster tires do?? Would be an interesting bit of info.

BoB

[zuzupwr]

I have a 2001 E/C 2WD with 14,000 miles.With piperack on and city driving I average 16.4-16.7 mpg just about every tank. Using hour meter reading divided into mileage comes to average vehicle speed of 28.3 mph. Been on same jobsite since buying truck and commute is only 12 miles but all stop and go. Very pleased with mileage under those circumstances. Have only made one short trip in truck to little stock car race in Talladega,AL. Removed piperack and shined it up before we left. Did an easy 75 mph 130 mile morning cruise over and an 80-85mph ride home(trying to run with team transports-now there's some good runnin diesels) Filled up at home that evening and we averaged 20.4 mpg. We thought something was going on when we only used a qtr. tank. Couldn't be more pleased.

[zuzupwr]

Wonder if the 500 hour engine run milestone has anything to do with the "sudden improved mileage" posts we've been seeing.

[Aluminator]

I drive San Diego to Phoenix about 380 miles and if the police are not out 17.5 if I stay near the posted speed 19.5-20 is no problem. It is sooooo easy to get rolling along at 85+ and not know it. My truck is from NM and doesn't have the CA smog stuff.

Dennis

[deerhunter7]

TXMAX you have about the same set up as I do. The only mod I did is the amzoil airfilter and removed the front side of the air box. That's on
the bottom half and about half the deep end. Adds
about a third more area. My milage all winter was 14 to 14 1/2 . Warmer weather went to 16 . Did that filter mod and last tank was 17 1/2 . About
50 /50 highway city. 6100 miles on truck. It's finally getting better.

[hapaschold]

finally got 17.5 mpg for my commute, 75-80 mph for 60 miles.

i started buying fuel from my heating oil dealer, he has a pump on the side of his building, got a pump key and pump my own. dont know yet what he s charging/gallon, but he said would be close to high volume truck stop prices.

thats when i finally got out of the 15-16 mpg range.
9200 miles on the truck.

[56Nomad]

Hi,

If my math is correct, the cost difference in getting 17mpg versus those folks getting 20 mpg
is about $13 for every 1000 miles if the diesel
fuel costs $1.50/gal.......... that should not
break anyone's piggy bank ;)

[Jomar]

Took a trip this past Feb.pullin my 30ft 5er, which means there was a 6x8 frontal area up there pushing the wind. We drove 3800 miles and the Dmax average 10.79 mpg overrall. There`s still some PSD guys wondering what that was that went by them, which means I wasn`t soft pedaling it.