?? for 3500 CC 4X4 Owners

[Big O]

I just returned from a 1600+ mile trip to Mo. I love the truck and consider it good on mileage in general, BUT not as good as the ZF6 SHOULD be. It seems that most of the same designed trucks (3500 CC 4X4) with the Allison is getting as good/better than mine with the 6 spd. I would like some feedback from similiar owners of Ally or ZF6. The truck weighted a total of 8800+ lbs, including the ATV.

On the way up, all freeway @ 75mph it got 16.6 mpg
On 2 lane, around Mo, it got 14.5 to 16.8 mpg
On the way back, all 4 lane @ 65, it got 18.9 mpg

Now I realize that at 8800#'s that is good mileage, but what confuses me is that I keep hearing of similiar trucks with the Ally getting better than 20 mpg. Any TRUTHFULLY info would be appreciated.

[mdrag]

Big O,

My truck is a '01 3500 CC 4WD Dmax/Allison. I stopped checking fuel mileage after our holiday trip ~2400 miles (included ~200 miles 4WD highway miles), 75-85mph, drivng style not at all directed toward fuel savings -> just below 15 MPG. Truck had only abut 2.5K total miles at the start of the trip. Many have said the fuel mileage improves after 10K or so....

It seems I get 14-15 MPG no matter if highway or around town. Probably could squeeze out a few more MPGs if I slowed down, but it would not be as much fun driving :D

[Big O]

mdrag --
At 75-85 you are just as good or better than mine, and that is auto vs manuel. Thanks,

[SoCalDieselNewbie]

Big O,

I too question the mileage that some folks are claiming to be getting.

Not that they aren't getting that mileage but at what speed and rpms...

First, my truck only has 2000 miles on it but I did just get back from a trip to Lake Tahoe. It is about a 920 mile round trip and I was empty.

On the way there, I was doing 75 mph @ ~2200 rpm... 15.7 mpg.

On the way back, I did 70 mph @ ~2000 rpm... 18.9 mpg.

5 mph less = an increase of 2.2 mpg

[Big O]

SoCalDieselNewbie
I guess that I incorrectly ASSUMED that the manuel would get better mpg than the auto! :confused: :eek: :confused: :mad:

[01_Duramax_Dually]

BigO
I have a 3500 CC LB 4x4 Dmax/Ally
I average 15.5 Daily driving which includes alot of stop and go, bumper to bumper traffic.

When I drive on trips with 5 people I figure I weigh a bit over 8500 with luggage and tool box, bikes and other family essentials. I average 16.5-17 going appx 80. Now I have gone on trips before some time back where I was required to go 55-60 due to people in the caravan and I got 21.9.

I would say 16 seems to be the daily average, 17-18 on freeway doing 65-70.

55-60 can get you 20+ but it is virtually impossible to go that slow....I know I cannot anyway...

The only MODS my truck has is the drilled out air box and AMSOIL 2 stage air cleaner.

Hope this helps.

[RWHP]

You are getting the same mpg as everyone else, just some people like fib. The best my truck ever got was 16.4, and the average is 15.5-16. Towing I get anywhere from 10.5-12 depending on the road and at 80+ speeds.

[markf]

Big O

I would love to get that mileage. I have a 2002 GMC CC D/A 4x4. On my first tow trip hauling 10,000lbs I averaged 13 mpg. I did go from sea level to 5,000'. Around town I am getting 15 mpg down hill with a wind at my back. I only have about 2,300 miles on my rig so I am hoping this improves as the beast breaks in.

2002 GMC 3500 CC D/A 4x4
SLT 40/20/40 leather bench
in the rarely seen pewter/neutral combo

[SoCalDieselNewbie]

01_Duramax_Dually,

You could always increase your tire diameter to lower your rpms. It might be worth a 1-2 mpg.

It should only take you a couple of hundred thousand miles to recoup the cost of the new unecessary tires and wheel spacers.

Just think of it as an investment. :rolleyes:

Big 0,

I really do not know what gets better milage the manual or auto... I just know that I set the cruise control @ 70 and was in override for the next 390 miles.

I just make sure that I fill the tank until I can see fuel in the neck because it is real easy to underfill a tank by 1-2 gallons.

It might take a few minutes to fuel up, because of foaming, but it eliminates false highs and lows in mpg.

[JEBar]

As noted below, '02 3500 CC 4X4 D/A...Just under 15,000 miles...70 mph max(often 65 mph) w/ 2-4 persons plus luggage on I-state 18.0-19.4 mpg (note: best mileage when not using cruise); 21 miles one way to work city/country mix 15.5-17.0 mpg; pulling trailer 18" w/ John Deere tractor, front loader, bush hog at 60-70mph on I-state 12-13+ mpg :cool:

[Timberline]

Your mileage sounds about right. Mine runs about 13-14mpg with 10,000lbs behind it and 18-19mpg empty. I did however get 21.5 one time but I babied it the whole tank full and kept the speed at 55-60mph. This was not an easy task by the way. Remember MPG falls off the faster you go. Even my Diesel Beetle drops 2-3mpg if I run it hard, but when it gets 50mpg+ it's still excellent.
Don't worry about your mpg and just enjoy the truck and it's power.

[Big O]

Thanks all. I have towed heavy weights, but not far enough to check mileage, just around home. If I get 12-13 towing, I would be satisfied.

I am not displeased with my current mileage, just suprised that the Ally seem to get just as good or better than the ZF6. I don't think another 6 spd. owner has replied.

When checking mpg, I try to always fill it to the level that only less than .05gal will go in without cutting off. This takes quite a while, but about the only way to determine the same level each time, due to the foaming. Thanks,

[Maverick]

My 3500 has 71,500 miles on it now and the best I have seen so far was 18 once and the rest 16-17 empty. A good heavy loaded average is 10-12.

[01_Duramax_Dually]

One thing I did forget was my towing mileage.

I seem to be right around where all you folks are mileage wise. I get 11-13mpg. 13.1 has been the highest from my records. The lowest was 9.3mpg but that was a Bonzaii trip to Las Vegas in which I averaged 80MPH towing my 10Klb trailer....

I have to say, These trucks are really a work of art compared to my previous '96 7.4 liter Vortec CC dually.. They have tons of power, have excellent road manners, and are easy and comfortable to drive. It honestly is hard to go slow enough to really get super gas mileage but then when you go from 5.5mpg to 11-13mpg and can maintain sppeds sometimes 25-30 MPH faster I am as happy as a "Pig in ..." Well you know... :D .

I have stopped my MPG log and now just check tank to tank to make sure the truck is on mark. I 100% agree with filling the tank until you see clear fuel. If you base it on a "Shut Off" you are tainting the data. Some places have very foamy fuel and can shut off prematurely. I fill until the pump shuts off, then I can typically add another 3-4 gallons after that initial shut off. Foaming is a huge problem with Diesel fuel.

Carry On... :D

[Searay90]

I find that my mpg drops off after I cross the 2000rpm level. at 65mph I have run three tanks where I averaged 18.5mpg. At 70, it falls off to 17.4, at 80 to 85mph it drops to 16.2mpg. These are all unloaded mpg's.

It seems the D-max gets thirsty above 2000 rpms!! That why I wish we had a 3.42 out back, or a steeper OD.

[Timberline]

Big O,
Mine is a 6spd! and love it!! though I wouldn't mind having an Allison in addition to my 6spd.

see my post above.