Duramax MPG Thread
#31
08-07-2008, 09:12 AM
Diesel Bomber
yeah i dont count on the computer becayse it is a average of what im doing. if its a regular week im getting somewhere in between 35-37 MPG but on a trip to arkansas i took on the highway i got 42 MPG once. i dont get as great mileage as a jetta because i got bigger car and bigger engine and now i will shut up because i just hijacked the thread
#32
08-07-2008, 12:29 PM
I have to post in this one, my truck on the highway averages a "Varifiable" 24.5mpg when I keep it set right on 70,, however, I DO have a manual tranny, and I do feaththe throttle for acceleration, and when on the "Big Road" I put maximum pressure in the tires. On a trip this summer to my mom's house at the beach on OAk Island NC, 351 miles from my driveway to hers, I used 14.32 gallons of fuel. I filled up and then went home and got packed and left, other than acceleration, and the fact that we started out @ 3AM to take advantage of less trafffic, my overall average mph was 63, and that is including highway and secondary roads and all. SO, 351 miles / 14.32 gallons = 24.51117318 mpg on the trip. 
OH, I forgot, I filled the tanke to the top of the filler neck before and after the trip to get an accurate, "hand calculated" measurement... the only thing that may have thrown the measurement off is the size of my tires, but I am not real sure how to make the adjustment for that., if anyone can take my calculations and make the adjustment to account for 285's tire size and then let me know I would appreciate that... and let me know how you make it...
OH, I forgot, I filled the tanke to the top of the filler neck before and after the trip to get an accurate, "hand calculated" measurement... the only thing that may have thrown the measurement off is the size of my tires, but I am not real sure how to make the adjustment for that., if anyone can take my calculations and make the adjustment to account for 285's tire size and then let me know I would appreciate that... and let me know how you make it...
#33
08-07-2008, 12:31 PM
He still isnt getting over 24 MPG now matter if he has a 5 gallon tank or 100 gallon tank. 
#34
08-07-2008, 04:45 PM
Diesel Wrench
thanks...
ie: the mention of the fact that they were off due to tire size...
but thanks for the effort...
ok, according to mapquest the actual mileage would be 330.95, using14.32 gallons = 23.11mpg
Last edited by bigdaddydiesel; 08-07-2008 at 04:51 PM.
#35
08-17-2008, 02:50 AM
#37
10-26-2010, 06:34 PM
Hey everyone, I am new to the forum. Well after reading all of the threads related to the Duramax fuel mileage, I can't help but feel that I am missing something and I need some education from all of you to help me out. I have an 05' Chevy Silverado 2500 HD 4WD Crew Cab Std Bed w/ 6.6 Turbo DMax. Truck has a 4" lift with 305 70/16 tires. I have an aftermarket AirAide system with an oil bath filter. Otherwise than that everything else is factory original. Most of the miles that I put on my truck are highway miles. I average approx. 140 miles/day on the highway and I am only averaging, when I am on my best behaviour, about 13.9 miles/gl. What could be the problem, or does this sound about right? 
#38
04-05-2011, 10:50 PM
i use diesel clean with cetane boost every tank(in the grey bottle). and my rig aint no reg cab short box
on secret is to keep your mass air flow sensor clean i use a good carb cleaner i do that every oil change. make sure it evaporates and doesn't leave any deposits
2003 duramax crew cab long box straight pipe exhaust AEM brute force intake Readylift leveling kit
and a Striker)...............so with that being said a long box has a 34 gallon fuel tank stock. So then with simple math you take 650 divided by 34....and that equals 19.117647. or take 750 divided by 34.....and that equals 22.058823. to me that kind of mileage is pretty average as everyone else in this thread has said many times. So tell me how your math he is getting over 24mpg????? And tell me how when you are calculating an AVERAGE OF MILES PER GALLON, tank size has no affect on the outcome?????
---AutoMerged DoublePost---
I really want to know how you calculated OVER 24MPG without using the size of the tank in the calculation??????????????
Last edited by truckin38s4x4; 04-05-2011 at 10:50 PM. Reason: Automerged Doublepost
#39
04-06-2011, 12:48 AM
I dunno how YOU calculate fuel mileage unless you use the dash.....not a bright idea.....but usually you take the total mileage divided by the amount of fuel in gallons and it gives you an AVERAGE of MILES PER GALLON. So if you read his thread is says............... (my truck is stock and empty and driving sane i get 650 - 750 miles out of a tank
i use diesel clean with cetane boost every tank(in the grey bottle). and my rig aint no reg cab short box
on secret is to keep your mass air flow sensor clean i use a good carb cleaner i do that every oil change. make sure it evaporates and doesn't leave any deposits
2003 duramax crew cab long box straight pipe exhaust AEM brute force intake Readylift leveling kit
and a Striker)...............so with that being said a long box has a 34 gallon fuel tank stock. So then with simple math you take 650 divided by 34....and that equals 19.117647. or take 750 divided by 34.....and that equals 22.058823. to me that kind of mileage is pretty average as everyone else in this thread has said many times. So tell me how your math he is getting over 24mpg????? And tell me how when you are calculating an AVERAGE OF MILES PER GALLON, tank size has no affect on the outcome?????
---AutoMerged DoublePost---
I really want to know how you calculated OVER 24MPG without using the size of the tank in the calculation??????????????
i use diesel clean with cetane boost every tank(in the grey bottle). and my rig aint no reg cab short box
on secret is to keep your mass air flow sensor clean i use a good carb cleaner i do that every oil change. make sure it evaporates and doesn't leave any deposits
2003 duramax crew cab long box straight pipe exhaust AEM brute force intake Readylift leveling kit
and a Striker)...............so with that being said a long box has a 34 gallon fuel tank stock. So then with simple math you take 650 divided by 34....and that equals 19.117647. or take 750 divided by 34.....and that equals 22.058823. to me that kind of mileage is pretty average as everyone else in this thread has said many times. So tell me how your math he is getting over 24mpg????? And tell me how when you are calculating an AVERAGE OF MILES PER GALLON, tank size has no affect on the outcome?????
---AutoMerged DoublePost---
I really want to know how you calculated OVER 24MPG without using the size of the tank in the calculation??????????????
John has 38's on his truck, his is not calibrated for 38's. so if he used the trip odometer to calculate, it will be thrown off.
you dont need to know the size of the tank to calculate mpg, as long as you fill it up to the top, then look at the fuel pump and see how much fuel you put in and divide it into your trip meter.
Last edited by 2500HeavyDuty; 04-06-2011 at 12:51 AM.
#40
04-06-2011, 06:23 AM
I would definitly have to agree with you on that. But in the original post the guys states 650-750 miles to a tank. doesnt ever mention how many gallons he put in his tank from the pump. so with that in mind a rough average would have to be calculted by the size of the tank or close to...so a 34 gallon tank...using round numbers 30 gallons used if you wanna push it that still is no where near 25-29 mpg. i definitly agree with you. im quite content with 18 in my truck as well
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