Wife and I drove the round trip from Phoenix to Tucson on Monday. Fueled at the Flying J on I-10 in Eloy for $1.61 per gallon. Mileage from Flying J, driving in Tucson, and then refilling at the J on the return to Phoenix was 18.6 mpg. That mileage was with the ac on and four people in the truck. Wife drove about three-fourths of the trip and she has a heavy foot.

According to my fuel gauge, 177.5 miles at 3/4 tank, I'm getting over 27mpg!! http://www.dieselplace.com/forum/smileys/Geek.gif


Sure would be nice if GM wouhttp://www.dieselplace.com/forum/smileys/Angry.gifld put in an accurate gauge and sender!!!Edited by: Oldman

$1.61 in Eloy is still a lot lower than in the Valley, huh? Sounds like your mileage is about right for that kind of trip. I drive a minimum of 5 mph over the limit most places and your mileage is pretty close to mine. Gotta love driving a beast that gets mileage like a mid-size car!

It would be nice to see some of the mileage claims that people make..


(I am NOT calling anyone a liar here!)


But all I heard before I bought my dmax was that they get 20mpg after the first 10k. That is empty highway miles.


Well I get 13.5-15(high) with mixed hwy/city driving.


Then I only get 16/17 on the highway running about 8 over the speed limit.


I now have 20k on the truck. I was just hoping for a little more..


And if this is all I have to gripe about with my truck then I say I am doing just fine..http://www.dieselplace.com/forum/smileys/Wink.gif

Hey Lonewolf, my claim above was nothing but sarcastic. I hate the cheap gauge/sending unit they put in these trucks. I was serious about having 177.5 miles and the gauge only dropping 1/4 . However, I know it's going to drop like a rock from this point on. My actual mileage is around 17 to 17.5. That's 80 miles per day, 40 of it is between 60 and 80 dpending on traffic. The rest is back roads at anywhere from 25 to 50 mph.

Most people who claim that their Dmax gets 21 mpg are right - when they're feathering it at 60mph with no headwind... lol

I have 38,000 fully documented miles (spreadsheet) that my '03 GMC CC/LB D/A has put on. I am averaging 18.1 according to my spreadsheet, and 17.9 according to the DIC.

I get about 14.5 hauling, & I can get over 21 on the freeway in cruise as long as I stay below 70mph. My average around town seems to be about 16.5.

I've heard about lower mpg Dmaxes & don't know why they get less than mine. Probably driving style.

Just took my first half-a**ed trip with the truck....280 miles round trip....hit a bunch of traffic so there was a lot of stop and go, and fuel gauge is now reading 1/2 tank. DIC is still showing a range of another 214 miles, which sounds about right. Truck has 2k miles on it, bone stock, trip was made empty, nothing in tow. If my calculations are right, that works out to @19mpg.http://www.dieselplace.com/forum/smileys/Cool.gif DIC showed the same during the trip.http://www.dieselplace.com/forum/smileys/Thumbs Up.gif

<TABLE id=HB_Mail_Container height="100%" cellSpacing=0 cellPadding=0 width="100%" border=0 UNABLE="on">
<T>
<TR height="100%" UNABLE="on" width="100%">
<TD id=HB_Focus_Element vAlign=top width="100%" background="" height=250 UNABLE="off">


i've owned my jimmy about 10 weeks...about 10 days after i adopted it a friend of mine and i made a trip trip new jersey, with about 39k on it...it was mostly interstate driving...my calculations showed that my mpg was a little over 16...i thot that was ok, but i was a little disappointed, as i thot i mite get more like 18mpg...


the truck rode VERY nicely and i love it...NOTWITHSTANDING that it's getting new injectors today with 41k on ithttp://www.dieselplace.com/forum/smileys/Dead.gif</TD></TR>
<TR UNABLE="on" hb_tag="1">
<TD style="FONT-SIZE: 1pt" height=1 UNABLE="on">
<DIV id=hotbar_promo></DIV></TD></TR></T></TABLE>

If an Dauramax owner, whose truck is under warranty, feels that the vehicle is not giving the mileage it should, might be able to get the dealer to connect an analyzer to the computer. The truck must be driven while connected to the analyzer. We had our Duramax tested with a five ton trailer behind on a six percent grade on I-17 in Arizona. According to the analyzer, we now have 97% efficiency, which gave us between 13-14 miles(average) per gallon on continous hills and grades on the interstate southward from Flagstaff. Non-towing on I-10 between Phoenix and Tucson yielded 18.6 on Monday. The mileage and diesel fuel price was posted earlier today on this website. Trying to find a dealer who is willing to make this test was not easy. It took nearly two months to find a cooperating dealer. My wife was ready to trade but now has changed her mind.

On a recent 900 mile (in one day) trip to Kentucky and back I recorded this mileage: Cruise set on 65 average mpg = 18mpg, cruise set on 75 or so, 21 mpg. From previous trips, 55mph gets me 23 mpg. This is for real mileage, this '04 doesn't have as much squirt as the '02 that it replaced. Oh yea I forgot to mention, the truck has 13K on it.Edited by: zsqure

Wow worth the trip to Eloy just for a fill up...


Tucson is at $1.79 at the cheap stations...





cmc

I have no clue why but my dads old 01 dmax dually never got over 15 mpg. It got 9 pulling 11.5 empty around town and if he was lucky he could get 15 on the highway. He drives very easy and never gets on the gas. Could never figure it out.

I am hearing alot about cheap gauges in the Duramax Diesels but I want to report that on my way home from work I decided to test my fuel systems computer. I was running on empty and the warning light had already popped on with the chime and I was showing 38 miles left to empty. I pulled into the fueling station and the gauge read well below empty and the tank took 24 gallons exactly without topping off. The owners manual indicates I have a 26 gallon tank and the computer was reporting an average of 19 miles per gallon. (I commute 50 miles round trip each day all freeway.) My point is the computer is right on the money so don't look at your gauge just keep the miles to empty displayed in the driver information window and you should never run out of fuel.


Love my Duramax so far!

just ran my first tank of fuel through since i purchased my 2002 silverado, all local mileage. back and fourth to work. I got 15.88http://www.dieselplace.com/forum/smileys/Big%20Smile.gif

'02 2500 HD D/A ext cab 2WD

June '03 43,000k 3400.1 mi round trip CA/Montana/CA traveling with wife, kayaking & camping gear w/15' double kayak on overhead rack; 70-75+ mph much of the way; no trailer hitch, fill into filler neck 1st & last = 19.3 mpg.http://www.dieselplace.com/forum/smileys/Big Smile.gif

Feb '04 49,000k CA/Salem, OR, 426.2 measured miles on I5, towing 21' TT approx 6500# @ avg speed 55-60mph on cruise, + 5th whl hitch, no passengers = 15.3mpg.

Mar '04 return Salem, OR/CA, I5, 531.7 measured miles no trailer @ 67 - 70 mph (2000 - 2050 rpm on cruise) + 5th whl hitch no passengers = 19.7 mpg
http://www.dieselplace.com/forum/smileys/Big Smile.gif and any time I "needed" to pass anything at 80+ mph did it but prob 95% @ 2000rpm. http://www.dieselplace.com/forum/smileys/Clap.gif

Total mis including in-between running around Salem, OR and trip to Vancouver, WA and back to Salem : 1328.1 mis for trip average of 17.3 mpg

... My point is the computer is right on the money so don't look at your gauge just keep the miles to empty displayed in the driver information window and you should never run out of fuel.


Hard to do if your truck doesn't have that function!!

2004cc lb7 sb 2wd..19combo driveing, about 50/50 highway,in town. Trip to myrtle beach 21.70, 75mph. I am very pleased Edited by: BRUCE

http://www.dieselplace.com/forum/uploads/E1E_Spreadsheet.jpg

<TABLE id=HB_Mail_Container height="100%" cellSpacing=0 cellPadding=0 width="100%" border=0 UNABLE="on">
<T>
<TR height="100%" width="100%" UNABLE="on">
<TD id=HB_Focus_Element vAlign=top width="100%" background="" height=250 UNABLE="off"> My first long trip to Maine ( round trip = 350 miles) , yielded 22 mpg. http://www.dieselplace.com/forum/smileys/Clap.gif This was 95% highway, with cruise set at 68 or so. I believe if I babied it without cruise on, I could get 24 highway. Love watching the instant mileage readout!!! Great way to realize max mpg. cruising speeds, especially on back roads. 45 mph seems to work great in o.d. gear, a bit tricky keeping it there though, as it likes to downshift near that speed with slight incline.</TD></TR>
<TR UNABLE="on" hb_tag="1">
<TD style="FONT-SIZE: 1pt" height=1 UNABLE="on">
<DIV id=hotbar_promo></DIV></TD></TR></T></TABLE>

I just checked my first tank of fuel on my 04 GMC CC 4x4 3500 LLY DMAX/ALLISON. 13.9. About 1/2 town 1/2 highway. I don't know what the dic said, it's usally not close, so I don't bother. I have a little iver 300 miles on it.


Al.

... My point is the computer is right on the money so don't look at your gauge just keep the miles to empty displayed in the driver information window and you should never run out of fuel.


Hard to do if your truck doesn't have that function!!





Sorry to to hear that Oldman.

My 2003 Duramax just turned 10,000 miles. I took a 109 mile trip last Saturday, in a heck of a head wind, 50 to 60 mph. I got 15.7 mpg. I seen fuel was 10 cents a gallon cheaper so I fueled up before the return trip, the wind had died down quite a bit, on the return trip i got 17.7. That is running empty. I figured the milage with a calculator. The DIC showed 16.7 in to the wind &amp; 18.3 on the return trip.

I pull my fifth wheel camper to AZ. in Dec. and got a whopping 8mpg. In a headwind on my return one time it was 6.4. With a tailwind 10.7. Empty just running around 20.5.

From what I have seen - mileage drops dramatically over when exceeding 68 mph. I think this is around 1800-2000 rpm.

How fast were you going to get those numbers?

- jeff

dmax lover I will agree with you on the 68 mph. While pulling my 28 foot 5er, I got a lot better milage running 65 -70. And it does make some differance running empty.

My D/A has always received 18 to 19 city driving. Combination driving is about 20. Straight highway is 22 at 70mph. Every tank I add 6 onces Performance Plus. My 01 Dodge Cummins HO 6speed was about the same. So were my other Dodge Cummins. This is what you should expect from a good diesel. http://www.dieselplace.com/forum/smileys/Big Smile.gif

I'm getting 18-19 empty, which I verified via calculator. My DIC is spot on, which from what I've read here is rare.


VeryOldDog, nice to see a fellow Volunteer here.

My DIC is quite close. It is always .5 to 1 US mpg optimistic. I always zero it with every tank and check it when filling against my spreadsheet. I think once I start running a tuner that will change.

Still 17.6 mpg mixed driving, with 21+ on the highway, at about 69 mph. I seem to have found a "Sweet Spot" in the motor.http://www.dieselplace.com/forum/smileys/Big Smile.gif

dmax lover, I tried all different speeds. 8mpg was traveling in flatlands with a minor headwind about 65. The 10.7 was flatland no headwind 63mph. My problem is weather i run it in tow haul mode or not, it would drop 50 rpm then downshift crank 2900 rpm 'till I gassed on it to make it upshift. It won't lug at all. Diesels are deigned to lug. Mine runs on rpm. No error codes for the transmission or the motor according to the dealer.


Mike

16.8 mpg running unloaded about 50% Hwy / 50% City. Mine also seems to like 67-69 MPH for best mileage. I prefer 75-80.http://www.dieselplace.com/forum/smileys/Big Smile.gif

The DIC says 13.8 mpg. That is 100% city stop and go at 4600 feet of elevation.

dmax lover, I tried all different speeds. 8mpg was traveling in flatlands with a minor headwind about 65. The 10.7 was flatland no headwind 63mph. My problem is weather i run it in tow haul mode or not, it would drop 50 rpm then downshift crank 2900 rpm 'till I gassed on it to make it upshift. It won't lug at all. Diesels are deigned to lug. Mine runs on rpm. No error codes for the transmission or the motor according to the dealer.


Mike











I remember seeing that another person had a similar issue - it was his trailer brakes; They changed the wiring a couple of years ago on the trailer brake controller "pigtail". If you use an older one - the brakes will be on when they shouldn't be...





footnote - I guess it is possible that you are very heavily loaded and 8 mpg "is what it is" - if that's the case, I wonder what your mileage would be with a big block gas motor - 5-6 mpg?


- jeff


Edited by: dmax lover

Here is what I have observed with my truck:


Highway and town mix unloaded with Edge on 90hp 13.3 mpg.


Highway and town mix unloaded Quad on 215hp 17.9 mpg.


Highway and town unloaded stock 16.5 mpg.


These readings were made driving the same route using same driving style (Fast) in similar weathe rconditions.


I am disappointed with my edge box, long cranking to start when warm, crappy mileage, must try to change power levels 15 times some times to get it to take the change.

dmax lover, I tried all different speeds. 8mpg was traveling in flatlands with a minor headwind about 65. The 10.7 was flatland no headwind 63mph. My problem is weather i run it in tow haul mode or not, it would drop 50 rpm then downshift crank 2900 rpm 'till I gassed on it to make it upshift. It won't lug at all. Diesels are deigned to lug. Mine runs on rpm. No error codes for the transmission or the motor according to the dealer.


Mike"


wow, i have never even heard of those low of numbers for a duramax, i also pull a heavy trailer, and drive like the devel, and am in the 14-17 range, imperial that is, and that is around the 73mph, i do run a chip that the tranny now never has to downshift, and run larger tires to keep the rpm down (at 73mph i am running 2000 rpm) keep in mind if i drive in the city you will see a reduction, but never that lowhttp://www.dieselplace.com/forum/smileys/Wacko.gif

dmax lover, I tried all different speeds. 8mpg was traveling in flatlands with a minor headwind about 65. The 10.7 was flatland no headwind 63mph. My problem is weather i run it in tow haul mode or not, it would drop 50 rpm then downshift crank 2900 rpm 'till I gassed on it to make it upshift. It won't lug at all. Diesels are deigned to lug. Mine runs on rpm. No error codes for the transmission or the motor according to the dealer.


Mike"


wow, i have never even heard of those low of numbers for a duramax, i also pull a heavy trailer, and drive like the devel, and am in the 14-17 range, imperial that is, and that is around the 73mph, i do run a chip that the tranny now never has to downshift, and run larger tires to keep the rpm down (at 73mph i am running 2000 rpm) keep in mind if i drive in the city you will see a reduction, but never that lowhttp://www.dieselplace.com/forum/smileys/Wacko.gif











Mine don't get much better milage and does the downshift/hunt for gear thing. Had it to the dealer but they say it is normal. I think when going 70 mph on a 6% grade it should not downshift and run the revs up to redline!

I have been reading these FUEL MILEAGE POSTS with some intrest because for me, like many others I just don't see the big numbers like some do.


For me I would say with my LLY the mileage is pretty close to what I got with my 02 LB7. All around mileage of about 15 MPG. Mostly city is about 13.5 - 14.5 and Highway about 15.5 - 17.0. Lots of Mountains to climb, short trips, sometimes too short to warm the enigine up, HOT days, COLD nights. Never really been better than that until this last week.


Just got back from Disneyland, which as you (should) know is in L.A., and is most notibly at sea level (or about). I live and play at 6000 FT. and above, and I have wondered how much difference there is between those of us at higher altitudes and those at lower altitudes. I ran at 80 MPH+ all the wayhttp://www.dieselplace.com/forum/smileys/Big Smile.gif and showed mileage increase from 16 MPG to over 19.0 as I reached L.A.


The trip home showed the same results, but the numbers declined as I got closer to home. This doesn't rule out the possibility that there is a big difference in fuel quality either, as I traveled 300 miles between fillups.


Is it possible that the Duramax is this sensitive to altitude? Maybe there is a change brought out by the humid CA. air? (I live in the DRY desert air!) I would love to get those 3 mpg's back all the time!


BTW, there was very little difference in MPG's between 75 and 82 MPH. I varied the speed quite a bit for a while and did not see enough improvement in mileage to justify extending the trip by any amount of time.


We should be back to running good old #2 Diesel now (not mixed) as it shouln'd get too far below freezing anymore this year), so I hope to see an increase from that as well.

I wonder how much of a difference the type of mudflaps, hood protector, tonneau cover, bars or steps etc. makes on mileage. Is it enough to account for some of the differences in mileage we see from truck to truck? If so I wonder how much of a difference.http://dieselplace.com/forum/smileys/Ermm.gif





Norm

2004 d/m cc sb 2wd, 19-191/2 combo driveing. 211/2 freeway 70 mph. I am a happy camper.

Well, just traded mine in on an '04 LLY yesterday. As soon as I get a little break in time and get my fifth wheel installed, I'll post new mileage reports. Hope it's better.





Mike

anyone have thoughts on why i'm only getting 11 mpg in the city. i have a cc lb 4x4. 02 w/27000 miles. recently mileage dropped from around 16 in the city to 11. i run around in 2wd and haven't done anything to the truck to cause this drastic change in mps. i'm wondering if it could be related to injectors?

anyone have thoughts on why i'm only getting 11 mpg in the city. i have a cc lb 4x4. 02 w/27000 miles. recently mileage dropped from around 16 in the city to 11. i run around in 2wd and haven't done anything to the truck to cause this drastic change in mps. i'm wondering if it could be related to injectors?


Ouch, I'd start checking things if mine dropped that much. Air filter, fuel filters etc. The worst i've gotten with mine was 12-14 mpg's and that was pulling a 30' travel trailer and bucking an 80 mph head/cross wind. I consistently get 600 miles on a tank empty.

EVERYBODY KEEPS SAYING THAT YOUR GETTING 16 TO 23 MILES A GALLON, WELL WHERE IS IT? I WANNA KNOW HOW MANY MILES TO A TANK AND SHORT BOX OR LONG BOX......I GET 365 PER TANK ON AN AVERAGE RUNNING IT ALMOST DRY. THEN FILLING UP 26.4 GALLONS THEN GET ANOTHER 350 TO 370 PER TANK...... I USUALLY GET AROUND 13.5 MILES PER GALLON AND THE DIC SAYS 16.5 TO 17....WHY IS MINE SO BAD? ANY INPUT?

I average 13 to 16 mostly in town some highway on my n01' D/A ec/ sb 4x4 bone stock with a little over 50k on it. This is by calculator as I dont have a "dic". I recently went on a 350 mile one way trip 95% mountain driving, 2 lane. Good head wind, about half the trip. My average speed was 85mph and at times hit 96mph. I got 17.622 mpg. On return trip, same route, no wind, same right foot and got 18.879 . Oh yeah, empty not towing, 1 passenger. I tow a home made, heavey duty car trailer with a toyota rockcrawler into the mountainsand the worst I have gotten is 13.321 and I never get passed! The absolute worst my truck has gotten was 11.227 and a dirty fuel filter turned out to be the problem. I Cant complain!!!! Sorry, didnt mean to be so long winded.

Just ran 225 miles across a mountain pass and back and got 20.54 mpg.One passenger and 400 lbs in the back coming home.Average speed was 63mph most of the time.Hot Juice 4.61 on level 4 on an 01 D/A ec 4X4 and 4" exhaust with 32000 miles.


This is the best so far to date and had minimal town driving so its all highway.


Blake

thanks durabluecrew, soon as i started to notice a marked change in mileage, i installed a k&amp;n fipk gen 2 cold air intake and also change the engine oil. i heard that when engine oil needs changed, fuel mileage will drop. the oil i went to was royal purple syn. and i was expecting a dramtic improvment in mileage but was disappointed. my next plan of attack is the fuel filter. i'll post later to let everyone know if that was the problem.

Hey alaska did your milage drop after the K&amp;N instal? I know it took about two-three tanks to normalize the milage after I installed mine. Talked to the tech at the dealership and he said it was common because the computer was adjusting to the new air flow ( it did come around so I guess it could be true).

durabluecrew, mileage did seem to drop a little more after air filter change but hasn't recovered yet. i must be around 5 or 6 tanks past the install though. hopefully it will come back. i am wondering if i have a bad injector or got some bad fuel? also, i notice that you live in canada and am wondering if you have syn. gear oil in the front end. i have heard that in cold climates, that the dealer will install syn. gear oil in the front diff. i am scheduled to go in for warranty work in a week and a half and i am having them look at the squeak in the front end and the thud in my tranny on start up and shut down. i will also bring up the fuel ecomomy as well. thanks for your info

I am running a 2002 stock everything with synthetic oil (delvac 1), a 6 speed manual trans, and a 3.73 rear end. During break in I got about 16 mpg, then by 20,000 miles it jumped up to around 19 or 20 mpg. Now, with 65,000 miles on the truck, it rarely goes below 21. I average 21 to 24 mpg calculated (trip miles/gallons filled) with estimated 70%/30% highway/town miles. Last tank I calculated 22.48 (310 miles/13.79 gallons). I think that my 6 speed trans might play a factor in my good mileage..? I am very very happy. I love the truck!

Ok, now I know I'm going to get called a liar, but that's ok.


Before I put the lift in my truck, I did a trip of about 1600km and averaged 28mpg. I had 285 tires on and running empty except for myself (210lbs). Like I said, I know I'm going to get called a liar, but I know what I calculated. I don't know what it is, maybe it's Canadian fuel or something, because I know diesel drivers around these parts aren't happy unless they get at least 22mpg. Once I put my lift and 315 tires on, my mileage has dropped down to about 17 which what a bunch of you guys are reporting. And for those of you who are curious if I calculated in larger tire diameters, yes I certainly did.


Maybe all you folks just need to come up to the great white north http://www.dieselplace.com/forum/smileys/Approve.gif

Have 6200 on my truck and filled up yesterday. All in city driving and I got 17.0 MPG. I really don't drive aggressive, but I am happy with this mileage............a lot better than my 8.1!! I went 324 miles and it took 19.0 gallons........the dic said I used 19.2 gallons........Edited by: vegasdude

Ok, now I know I'm going to get called a liar, but that's ok.


Before I put the lift in my truck, I did a trip of about 1600km and averaged 28mpg. .....





Is that imperial gallon or US gallon?

Uh, honestly I'm not sure. What I do is take Litres and divide by 4.55. http://www.dieselplace.com/forum/smileys/Embarrased.gif


Which on is the bigger of the two just for future referrence?Edited by: Zorganov

Uh, honestly I'm not sure. What I do is take Litres and divide by 4.55. http://www.dieselplace.com/forum/smileys/Embarrased.gif


Which on is the bigger of the two just for future referrence?





That would give you imperial gallons. 3.7854 Liters per US gallon.

OK, see, I said I'd be called a liar http://www.dieselplace.com/forum/smileys/Big Smile.gif


I've calculated it out now according to the US gallon. I'm sitting around 23mpg then.


Thanks Dmaxcan for the correction. It's hard to keep track of all these differences between the USA and Canada.

Zorganov, that is good mileage especially since you did the math. I,for one, knew you had bigger gallons up north. Later! Frank http://www.dieselplace.com/forum/smileys/Big Smile.gif

13.5 and 14.5 on a good day......is mine broke or something?

My mileage became more more consistent once I passed 8500 miles--I have 11200 now. GMC D/A 04/LB7 CC 4X4


When new--my standard all freeway run netted between 21 and 19. This was with stock tires--between 55 and 65 miles per hour.


Upgraded to 265 Revo's--mileage initially dropped around 1mpg.


Now--after 8500miles--63 miles per hour--I consistently use 6 gallons for 136mile trip(GPS). My DIC is usually 0.1 to 0.3gal high. I believe this because I have checked with the same fuel pump (at the my fuel lot) and I fill up all the way up to where I can see the fuel (you are not suppose to do this). So the DIC is dead on.


Now my 136 mile trip uses consistently 6 gallons (per DIC give or take a tenth)=22.6mpg @ 63 cruise. At 80-85mph cruise I get 15mpg on the same trip. City is around 14mpg--lots of lights and traffic in Los Angeles.


Ron

I just returned from a 1500+ mile trip. Combined mileage for the trip was 18.4. We used 82.2 gallons. This with 3 people, 3 suitcases, a cooler full of drinks, some fishing gear, junk purchased, idling for extended periods, and four-wheeling for maybe 25 miles (not rough, just a little muddy), hauling 1/2 ton of corn for 25 miles (in the mud for 5), slogging through flooded streets in Calsbad, NM, and so on. I am thrilled with that mileage.


On edit: Oh, and I don't dog it. I'm running 5-10 MPH over the limit on the higway which in Texas means anywhere from 65 to 85 MPH. Most of the highway time was at 70 MPH or faster.Edited by: Kartattack

Just ran the reverse trip I reported in my March 10 post to this thread on page 1.

'02 2500 HD D/A ext cab 2WD

April 1, 2004 :
Traveled from northern CA to Salem Oregon on I-5. 585.7 measured miles no trailer @ 67 - 70 mph (2000 - 2050 rpm on cruise) + 5th whl hitch, no passengers = 18.0 mpg
and any time I "needed" to pass anything at 80+ mph did it but prob 95% @ 2000rpm.

Apri 4 & 5, 2004 :
Salem, OR to northern CA on I-5. 568.2 measured miles on I-5, towing 21' TT approx 6500# @ avg speed 55-60+mph on cruise, + 5th whl hitch, no passengers = 14.9 mpg.

Total mis including in-between running around Salem, OR : 1153.9 miles for trip average of 16.3 mpg.

Always fill up into fill neck so that I can touch the fuel with my finger on the beginning and ending fuel fill - all results are hand calculated as the '02s are DIC-less. (couldn't resist that)

Offhand I would have thought bringing the trailer home from Salem would have given better fuel economy than vice/versa but all in all I feel pretty good about the mileage so far. It will be interesting to see how I do with the 8500# fith wheel in a couple of weeks.

I'm getting DIC around 15 for city driving, and if I reset DIC for highway trips it will read 20-21 @75-80 if the traffic is flowing freely enough to maintain that speed and not have to accel/deccel too often.


Last Fall I took a 3k camping trip pulling 25' TT, lots of miles on mountain roads such as Blue Ridge Pkwy and interstate speeds as fast as 75-80 DIC said 14.1 OA when I got home.


One thing I have noticed here in the rolling hills of GA is that if I pick a throttle setting to maintain the desired speed on level ground (unloaded), and hold that setting up hill and down NOT using cruise control, The DIC doesn't show near as much dropoff going up hills as it does if you punch in cruise and let it do it's thing on maintaining speed up the hills.

Total Miles = 15652


Total US Gallons = 1004


Total Mpg= 15.59





This is mostly lighted loaded without a lot of in town driving. Also, I am completely stock and the numbers reflect winter as I have not owned the truck through a summer yet.

Since getting my 285's I haven't really had a trips till now. Running 75-80 I got 15-16. But when I dropped to 65+/- the mileage went up greatly. I guess those extra rpm's cost a little mileage.

A big factor is wind resistance. IIRC, wind drag increases by a squared term. Using your example of 65mph to 75mph, drag would have an approximate change of (75*75)/(65*65), or about 33% increase.

37500 with a 15.6 mpg lifetime in 1480 hours. Highway (72-75) is around 18 and in town is ~15.

Rickles,


These guys can correct me if I am wrong but I believe running 285 tires lowers your speedometer and odometer about 8%.(noted that in your signature). When calculating your MPG you must add 8% to your total miles driven, before dividing by gallons. Of course this doesn't apply if you have corrected your computer using a programmer.

I just made my first trip pulling our new 32.5 5er to Myrtle Beach about 180miles or so from Charlotte. Just me &amp; the wife running the ac mixed highway/old country roads with speed zones,ran 5-10 miles over the speed limit the whole way &amp; averaged 12.2mpg by the calculator.I was amazed, I expected less while towing expecialy with atrailer as big as mine. I just had to tell it to somebody!!!








03 dmaxextcabsboxw/linex,mega filter,Jayco305bhs