LBZ Fuel Mileage

**tsitts** · 07-02-2006, 19:43

Just traded my 04 2500HD LLY 38000 miles on a new 06 3500 LBZ Dually, drove from Denver to KC to drop off old truck and pick up new. 80 mph the whole way 570 miles.

Outbound trip in LLY 16.9 mpg overall
Return trip in LBZ 11-12 mpg for the first 300 miles, 15.3 mpg in the last 270.

Next day 100 miles of local driving 600 miles on odometer 55-65 mph, 15.9.

LLY 5 speed allison 80 mph, 2400 rpm
LBZ 6 speed allison 80 mph, 2050 rpm

Looking good to beat 04 mpg once fully broken in.

**Prestonia24** · 07-08-2006, 21:46

First Post Here, let me say I thought I knew a lot about diesels before i bought one lol, (I drive a 2005 Ford E350 Ambulance w/ a PowerStroke Diesel about 2,000 miles a month). Definately knew that i didn't want to drive a Ford Truck (Never have liked them, their diesels don't impress me much)
- but there's always room to learn a bit more, and these forums are filled with information from Diesel owners.

I'm 21 Years old and work as an EMT for a local ambulance company here in SoCal, and just recently purchased a 2006 Chevy Silverado 2500HD w/ the LBZ Duramax 6.6L Diesel, and i'm quite impressed. I'm dwindling down the last quarter of the first tank (the tank the dealer purchased lol) and the DIC is saying i'm only getting 13.5mpg, but hey, i know that the mpg will get better as it gets 'broken in'. My 01 Sierra got 14mpg and i have much more truck than before.

The 6th gear on the new Allison tranny is wonderful, i can cruise down the freeway at 75-80 no sweat, and the acceleration is terrific for a diesel (at the cost of fuel economy, but w/e).

I purchased the truck because i wanted a larger cab and 4x4 capability, for when i go skiing in the winter (my old 2wd w/ snow chains didn't cut the mustard, even for California mountain driving).

I met many Duramax owners before i purchased one myself, and they all told me how wonderful their experience had been with their GM truck.

Plan to put some larger/wider tires and when the Banks aftermarket kits come out for the LBZ Diesels, i'm thinking about changing the exhaust and some aftermarket guages as well.... After all, 360 HP is 'sufficient' at this point, but who knows, i might want 'more' lol....

**hapaschold** · 07-09-2006, 04:00

Originally Posted by Prestonia24

First Post Here, let me say I thought I knew a lot about diesels before i bought one lol, (I drive a 2005 Ford E350 Ambulance w/ a PowerStroke Diesel about 2,000 miles a month). Definately knew that i didn't want to drive a Ford Truck (Never have liked them, their diesels don't impress me much)
- but there's always room to learn a bit more, and these forums are filled with information from Diesel owners.

I'm 21 Years old and work as an EMT for a local ambulance company here in SoCal, and just recently purchased a 2006 Chevy Silverado 2500HD w/ the LBZ Duramax 6.6L Diesel, and i'm quite impressed. I'm dwindling down the last quarter of the first tank (the tank the dealer purchased lol) and the DIC is saying i'm only getting 13.5mpg, but hey, i know that the mpg will get better as it gets 'broken in'. My 01 Sierra got 14mpg and i have much more truck than before.

The 6th gear on the new Allison tranny is wonderful, i can cruise down the freeway at 75-80 no sweat, and the acceleration is terrific for a diesel (at the cost of fuel economy, but w/e).

I purchased the truck because i wanted a larger cab and 4x4 capability, for when i go skiing in the winter (my old 2wd w/ snow chains didn't cut the mustard, even for California mountain driving).

I met many Duramax owners before i purchased one myself, and they all told me how wonderful their experience had been with their GM truck.

Plan to put some larger/wider tires and when the Banks aftermarket kits come out for the LBZ Diesels, i'm thinking about changing the exhaust and some aftermarket guages as well.... After all, 360 HP is 'sufficient' at this point, but who knows, i might want 'more' lol....

reset the mpg calculator, you ll see instant increase while running on highway.

**D-MAX** · 07-18-2006, 19:26

I have 890 Miles so far and am geting 18.8 mpg, better than my 02 Duramax at the same miles, and my 02 at 58000mi was getting 20 to 21 mpg with a best of 22.6 mpg at 65mph so I hope my 06 will do as good or better!!

**jevanb** · 07-20-2006, 03:09

filled up yesterday after first tank after dealer, 636miles total, tank was topoff, ran 377miles @ 18.17gals=20.7mpg, truck said i used 20.7gals total=18.2.
I run 56 miles, mostly hwy miles to and from work @70mph about 15 city to get out @ 35mph. A lot better them my 04 cc 4x HD 6.0

**nailem** · 07-21-2006, 08:43

im thinking of buying the new LBZ and all this info has been great. i was woundering what gear ratio you guys had. i heard it makes a big differance in the mpg. im not looking to do any heavy hauling so the 3.42 would work for me. what do you all have?
thanks

**jevanb** · 07-21-2006, 12:30

373 is all you can get unless u get the 3500. with the 6speed it is geared final to act like a 342

**JohnC** · 07-21-2006, 14:34

Yeah, the new 6 speed Allison has a double OD too. Can't immagine going any longer, unless you spent all day cruising unloaded at 100 mph...

**cowboywildbill** · 07-26-2006, 04:43

We just picked our 06 D/A 3500 4X4 C/C. It had 28 miles on it. I only drove it about 9 miles and dropped it off at an RV dealer to get a B&W gooseneck hitch installed. The fuel mpg computer said it was getting 9.7 mpg average.
I sure hope that the computer isn't accurate. We were getting an honest 15.8 from our 02 "same model truck" just running around town and not babying it. And 10-13.2 mpg towing. I will have to run a tank of fuel thru the 06 and do the math.

**JohnC** · 07-26-2006, 08:27

Originally Posted by cowboywildbill

It had 28 miles on it. I only drove it about 9 miles ... The fuel mpg computer said it was getting 9.7 mpg average.

Did you reset it before getting the 9.7 mpg reading? If not, it's factoring in the first 28 miles, where it probably never went faster than 15 mph...

**caddy527** · 07-26-2006, 19:07

I have less than 700 miles on my Sierra crew LB SLT and I'm getting 14.8 around town according to the computer. I gassed up, reset my fuel meters and was on the highway for about 15 miles and the AVG meter read 16.8. I'm expecting great things form this truck and good milage is just the beginning.

**cowboywildbill** · 07-28-2006, 06:35

We just traded our 02 in for an 06 D/A C/C 4X4 Dually. At first the computer said we were getting 9.4. But then we topped it off and I drove about 250 miles. I topped off again and did the math. I was getting 15.9, this was in town stop and go. The computer was saying 14.8. I think it is a little under the real milage. I was getting about 15.5 to 16 running around,and driving hard also in our 02 GMC. I think the new one will do a little better once it gets broke in.

**rtigert** · 07-31-2006, 22:55

Picked up the truck in Joplin, Missouri 404 mile trip home. Accelerated/decelerated probably 200 times during the trip, never on cruise, continuously loading and coasting the engine. Averaged 72 mph, DIC said 16.1mpg, hand calculated 17.65mpg. I couldn't be happier at this point!

**EdHale** · 08-02-2006, 14:43

I picked up my new LBZ on 7-5-06. It is a GMC CC SB and is bone stock including stock tires. Here is my mileage so far. Some of these fillups are towing a 4,500 lb boat and trailer, some with a 900 lb empty boat trailer and some with no trailer. The 19.5 mpg was with no trailer and 75 mph over 250 miles. The rest is a mixture of highway at 75 mph and 2.5 miles a day to work each way (not helping at all).

Total truck miles MPG
244 18.5 no trailer
478 15.0 4,500 boat
806 15.5 4,500 boat
1,185 19.5 no trailer
1,512 17.5 no trailer
1,783 15.6 no trailer 6,500 boat for 10 miles
2,066 17.8 empty boat trailer
2,306 16.8 empty boat trailer

I have to say the 16.8 was partially due to entering the interstate, with the empty trailer, and a "youngster" in a souped up Honda Accord (you know the one with the big oversized muffler that sounds mean!!!!) attempted to pass me while I was still in the acceleration lane. I just couldn't stand it and when he got up beside me, making a lot of exhaust noise, I punched it and left him with a silly grin on his face. By the time I was at 75 mph I just punched cruise and he never ever came up on me for the rest of my trip until I got off of the highway. This LBZ is a big step up from my '98 6.5. Smiling..............Ed

**caddy527** · 08-18-2006, 16:04

I just turned 2000 miles and got 18 mpg on the last tank. No highway but some 50mph stretches. I put in Amsoil at 1600 engine and rear. Before that I was in the 16 - 17 range. Don't know if it's the oil or the truck breaking in but I'm not complaining.

**FBJR** · 08-18-2006, 20:11

I have noticed the DIC is about 1 MPG under too. Getting about 15.8 on the first tank.

Makes me wonder how far off the speedo is to start?

Just got the Diablo and did the 65 HP tune with corrected tire dia of 33 inches. On the freeway it said I was going 40

when it was really about 65. Then got a brake warning for gosh sakes!!

But I could really feel the diff

Going to reset tonite using tire size vs dia and see if it takes and the code goes away.

FB

**EdHale** · 08-20-2006, 13:19

I just got home after a 500 mile weekend trip. The first half of the trip was all highway at 75 mph, removed a 7000 lb boat from the water and towed it 2 miles to a gas station for fuel, then two miles back to the launch. The rest of the trip was at 70 mph home. averaged 19.0 mpg for the entire trip. Total miles on my 06 LBZ right now is 3,300. Ed

No towing except for the 4 miles with the boat.

**cowboywildbill** · 08-21-2006, 06:39

Filled up and did a short empty non-towing " semi Highway trip" Some stop and go on a four lane Highway a few lights toward the end. About 135 miles round trip, the computer said we were getting 19.4 at one point. It mostly was saying average of 17.4 while we were at 55 to 65 mph. It seems to be getting better and we only have 1300 miles on it so far.I did an oil and filter change at 1,000 miles Rotella 15w40. I will go with synthetic Rotella after a few more oil changes. I'll post again after I do the math on the last trip. I think maybe about a 16 mpg overall so far best guess.

**Docklobster** · 08-21-2006, 15:45

Just returned from my first 1000 mile trip. 1500 miles on the engine now. Ran the AC the entire way, truck is stock. DIC read 11.2 MPG towing my loaded trailer ~9000lbs. Basically southern CA over the grapevine to monterey and back, AVG speed 55 to 60mph.

The MPG did drop a little when I smacked a cow returning over the grapevine!!

Truck didn't get a scratch but the trailer has some damage. Cow didn't fare too well, but I was the second person to hit him... Shocks bottomed out but I don't "think" anything was damaged we hit hard, I'm going to the dealer this week to double check everything...

**soot** · 08-22-2006, 21:41

I'm starting to think that you need to get 25k+ miles on a Duramax to get consistantly good fuel economy (my '04 LB7 was the same). I was stuck in that 18.5 to 19.2 range for a long time (this is on long Interstate drives), but this past week, I've been getting 20+ mpg with ~26k on my LBZ. Monday I got 20.42 mpg & today I got 20.07, both 300+ mile trips at 70+ mph, hand calculated & using my GPS to track total miles.

Not that I wasn't impressed before, but I'm REALLY starting to like this truck.

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