Real world mpg?

Tjmaxx

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Jun 7, 2014
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I've read a few threads I found doing a search but I'm wondering what everyone mpg is stock or with mods? I currently have a 08 6.4 f-350 and average a hand calculated 16-17mpg city (not sure on highway as I rarely drive highway unless I'm towing my snowmobile trailer which is a 2 place enclosed and I've seen 15mpg with that trailer). I am tuned and deleted, I could achieve slightly better mpg if I switch to less aggressive tires I currently run 33" duratrac's. I've been contemplating switching to a 03-07 duramax if I can lower my payment. I'd plan on doing tune, exhaust, and intake plus a few other mods. Lmm's are not totally out of the question either. Thanks in advance.
 

PACougar

Active member
Jun 27, 2012
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El Dorado Hills, Ca
Like I said, it'll be around 18 in the city. I suppose if you drive with a lite foot and you buy a RC/LB and then lower it/strip some weight out of it you could see 20 or 21. There's no magic here, it'll be fairly comparable with your 6.4.
 

mike diesel

I'm alright.
Sep 6, 2012
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SLC, Utah
Stock height, on stock height tires I get 16 highway and 14 city. I've never once out of 2 duramaxes and 2 cummins get me anything better. Don't expect any miracles or false hope when you "hear of" people getting 20+ mpg.
 

Utahski

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Oct 20, 2008
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Northern Utah
My LLY was getting about 18 highway, stock with Edge/Attitude on #3. After Mike L did the trans and a 6sp conversion, highway went to about 19-19.5......this was down around sea level. Then stock and MPI twins (stock turbo) with Rob's EFI tunes, first fillup coming back from Boise was 22mpg hand calculated (same on the DIC).....air the temp was 10-15*F. A couple months later on a 30 gallon trip, with a bunch of full throttle stomps and some mt driving, hand calculated was 22.5mpg. Now with so much done I have no idea, but it takes almost no throttle to go 70 and I'd guess highway mileage is close to what it was before.
 

PureHybrid

Isuzu Shakes IT
Feb 15, 2012
3,327
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Central OH
What kind of city do you live in that you can get 18mpg LOL.

When I was driving my truck everyday in town ONLY it would do 12-14. On the highway it will do 20-21 with the current setup. With a tune and stock tires I saw 23 ONCE. Pulling a 18ft enclosed trailer with my bike sucked it down to 16 traveling 70-80mph.
 

PACougar

Active member
Jun 27, 2012
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El Dorado Hills, Ca
What kind of city do you live in that you can get 18mpg LOL.

When I was driving my truck everyday in town ONLY it would do 12-14. On the highway it will do 20-21 with the current setup. With a tune and stock tires I saw 23 ONCE. Pulling a 18ft enclosed trailer with my bike sucked it down to 16 traveling 70-80mph.

Sacramento, Ca. If I nursed it around town I could get 18. In general I would get 16 in town driving normally.
 

vern650

Member
Mar 27, 2014
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hyrum, ut
my lly averages 15-17 in town and has broke into the low 20s on the highway. If you can find a dmax with a manual trans that will help mileage alot, my buddies got an '04 lb7 zf6 with the usual bolt ons and ats tuner and averages 19-22 in town hand calc.
 

Tjmaxx

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Jun 7, 2014
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My. "City" driving is southern Wisconsin lol so it's more like country roads with a few stop lights and stop signs . I don't want a manual unless it's in a car.
 

zf>allison

you never had your car.
Apr 30, 2013
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elsberry mo
my lly averages 15-17 in town and has broke into the low 20s on the highway. If you can find a dmax with a manual trans that will help mileage alot, my buddies got an '04 lb7 zf6 with the usual bolt ons and ats tuner and averages 19-22 in town hand calc.


My 02 zf regular cab best was 21.9 full weight on stock sized mud tires. With a banks stinger kit which was waste gate controller, 4 inch exaust, and a 80 hp tuner

My crew cab 01 zf full weight has also seen 21. But it has efi and all the stuff in my sig. That was hand calculated highway not really being the most light footed.
 

DAVe3283

Heavy & Slow
Sep 3, 2009
3,681
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Boise, ID, USA
My. "City" driving is southern Wisconsin lol so it's more like country roads with a few stop lights and stop signs . I don't want a manual unless it's in a car.
That kind of driving, and a Duramax should get 16-18 MPG, depending on how light your foot is. With the stock tires, you might be able to sneak it up toward 20 MPG with a good tune.

On the highway, it should do fine. Towing expect 15-16 MPG. My brother and I both get the same towing mileage, despite me having a CCSB and him having a RCLB (his weighs 2000 lbs less, gets the same towing mileage).

If you're happy with the truck you have, I'd stick with it. You won't see any major mileage changes (either way) coming to a Duramax. If the payment is much lower, then it might be worth it. Just remember on the LB7s (03 - early 04) the injectors tend to fail and are a pain (and $$$) to change out. So factor that into the cost of ownership.
 

OregonDMAX

NOT IN OREGON, NO DURAMAX
Apr 28, 2013
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Goodyear, AZ
Keep in mind the LB7's have always gotten better mileage then the lly and newer models.

I get hand calculated 16 city 20 highway if I drive it like I should. And this is at a drastically varying elevation of 3,000-5,500 depending on what side of town I'm on and then to work on highway it's 4-7k elevation increase.
 

Al's max

Member
Jul 29, 2014
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Texas
I've owned a lly, lbz, and two lmm's. I've gotten 14 city in every one of them. My lly was a zf trans and was the best on highway. I haven't heard of many 6.4 getting what your getting in town.
 

fast03

Active member
Jun 15, 2008
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Rancho Cucamonga
I would hate to follow some of you guys in town! 16-18 in town holy crap. I get like 12-13. highway around 18-20. I also don't know what you guys tow, but 12k fiv'r gets me about 10 running 65-70
 

Mike L.

Got Sheep?
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Aug 12, 2006
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Fullerton CA
I would hate to follow some of you guys in town! 16-18 in town holy crap. I get like 12-13. highway around 18-20. I also don't know what you guys tow, but 12k fiv'r gets me about 10 running 65-70

You are getting the same mileage as I am Steve.
 

Akers

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Jun 20, 2014
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I would hate to follow some of you guys in town! 16-18 in town holy crap. I get like 12-13. highway around 18-20. I also don't know what you guys tow, but 12k fiv'r gets me about 10 running 65-70

Same here as well.