I know this subject is talked about a lot on this forum. What are the mpg's of anyone who does a lot of stop and go driving . My truck is getting around 10 mpg plus around town, that blows. The dic is close to that and on the hyway I get 19 mpg plus depending how hard my foot is on the throttle. I just hand cal. today and had 10 plus mpg 90% stop and go driving. I have the EGR blocked was wondering if that has anything to do with it or is the winter blend of diesel a killer of mpg

I get about 14 to 15 mpg in the city, 18 to 19 mpg on the highway.

I get 12.5 average in the city commuting 10 miles round trip in all stop and go traffic. I have my speedo adjusted(predator)for my 265 size tires and I hand calc every time.

i'm seeing about the same kind of numbers as ben.

except if i'm unloaded, 100% freeway driving @ only 60mph on I-90 (super flat) i get 21mpg.

Stop and go driving I am seeing low 14's as well. My average speed per tank of gas is 24mph.

Short tripping will kill the MPG. I drive 5 miles one way to work. At the end of the week, the mileage is in the mid 16's. Three stop signs, no stop & go. On the highway the mileage varies from 17 to 20, depending on speed. Once I go over 2100 RPM in cruise, the mileage starts falling off. It seems to like 17 MPG @ 70 MPH.

Everybody's mileage will be different. Even different people driving the same vehicle over the same course day after day will get different mileage.
I have even had a fellow call me a liar here on the board because he was only getting ten to twelve MPG. What can I say? He either has a real problem with his truck, the way he drives it, or both.
Said he "drives it like a granny." (Granny from Hell, probably!)

Britt

I just looked at my read outs on the DIC 773 miles, 50 hours and 10.2mpg. Between the winter blend and 5 to 10 minutes of fast idle warm up the last three weeks the mpg is down. All of my driving is empty and under 50 mph with 3 miles maximum between stops except for 6 hours of plowing snow. I reset the mpg DIC for snow plowing and it read 2.3 mpg that day. The best I have got was 14 mpg in October before it got cold. Winter blend and warm up time will kill the mpg. My 1998 K3500 with a 454 got about 6 mpg in the winter.

Stop and go, unloaded,winter blend and driving like a corpse. 13 to 14..........:shake:

I guess between winter blend and warm ups it's a killer on mpg. I was getting 15 to 16 combined city anad hyway driving hand cal. but now like I said it's 10 to 11 . I use diesel kleen, the truck seems to be running great and sounds good, all but the mpg, ain't happy:( Thinking about taking it back to the dealer and see if maybe the ECM is off somewhat any ideas

I could be off here but since I put on a new fuel filter, my in town MPG seems to have increased back up to 15ish. Over the past couple months it seemed to have decreased to 10-12, this is based off of the DIC which seems to have been quite close to hand calced in the past. I was forced into a filter change because of the truck cutting off at 2KRPM this week, truck has 10K miles. I could just be imagining things though.

I could be off here but since I put on a new fuel filter, my in town MPG seems to have increased back up to 15ish. Over the past couple months it seemed to have decreased to 10-12, this is based off of the DIC which seems to have been quite close to hand calced in the past. I was forced into a filter change because of the truck cutting off at 2KRPM this week, truck has 10K miles. I could just be imagining things though.
My truck has 12k on it and I also was thinking about changing the fuel filter , hope it works

Get about 14 + or - a few tenths when in Vegas traffic. Combined moderate traffic and some road time a little better than 17 and pure highway at 69 to 70 mph between 20 and 21 mpg. Pure highway is generally with 2000 lb load, no tow.

I've had my truck almost a month (1,800 miles). Yes, cold weather and short trips can kill mpg. However, once the truck is warmed up, City driving averages about 15.7 mpg. On the highway, I was getting around 19 mpg doing 70 mph.

Once the truck fully breaks in, Spring comes, Winter fuel goes, I expect to do even better. When I traded in (dare I say) my Ford Sport Trac (4.0 with 5spd) I used to average 10-11 mpg City. Net, net...all things considered, no complaints from me.


Once you go Duramax you'll never go back.:hail:

JAFO

Well I figure it must be the fuel filter cuz I was getting 15,16mpg combined just recently. Truck has 12k on it so what else could it be:confused:

My last tank hand calc'd at 17.0 mpg. Total was 523 miles, 360 miles of highway at 70mph and the rest was city stop and go. Stock truck. Used 30.6 gallons.

I'm getting 16-17MPG on my city commutes.
Average speed during these commutes is 28-30 MPH - as reported by the DIC.

My fuel mileage is all hand calculated. The DIC reports 1-3 MPG better mileage with the Edge/Juice running, and about 1 MPG better without it connected.

Hiway mileage is in the 18-20 MPG range, depending on speed and wind.
Loaded (towing an ~8,000lbs TT) drops to 9-13 MPG, depending on wind and speed. I keep my towing RPM at 1,900-2,000 for best mileage.

Henry, what settings are you running your juice on?

Mine has ranged from the high 9's to 13 in town with stop and go driving, depending on how much I'm mashing the go pedal. One thing I've noticed is that I have to be really careful to top off after the pump clicks off. With the foaming, its really easy to be inconsistent. I've been able to add almost two gallons after the pump clicks off and this amount could obviously throw your calculations way off.

Just happened to check this morning. DIC is down to 15.9 mpg. Warm-up and winter blend are the biggest culprits. It has nothing to do with how much fun this thing is to drive. ;) I'm doing about 50% highway (mostly @ 65+ mph) and 50% SnG.

Just happened to check this morning. DIC is down to 15.9 mpg. Warm-up and winter blend are the biggest culprits. It has nothing to do with how much fun this thing is to drive. ;) I'm doing about 50% highway (mostly @ 65+ mph) and 50% SnG.
I just got done talking to the service manager and he said the same thing.
My truck only has 12k on it and it is running great. No bucking , no hestations nothing, or stalling so he said it ain't the fuel filter. The winter diesel blend is as you say the abig culprit

Towdog. You may be fine...until you get stranded. Your fuel may be different from mine, but at 10K miles, my filter pleats are blackened all the way up the filter. You may want to just change it and find out where you stand right now. Good luck.

I am getting 13 to 15 mpg city driving stop and go...One thing to remember about these trucks, they are made to cruise highways pulling stuff and I think a everytime you hear that turbo spooling up, mpg's go down.
By the way, I change my fuel filter every 10,000 miles.

stop and go driving is right at 15.7 and at 2K rpms is 71.8 mph according to garmin gps and goes 441 miles before light came on thats 23.5 gallons to fill up. so thats 18.7659 mpg.

Towdog. You may be fine...until you get stranded. Your fuel may be different from mine, but at 10K miles, my filter pleats are blackened all the way up the filter. You may want to just change it and find out where you stand right now. Good luck.
That's ok I have towing included in the insurance, seriously though I will change the filter very shortly

Hi All and Merry Christmas. Still getting great mileage. Even on winter blend. Still around 19 mpg. Just for the heck of it, I divided the total miles driven by the total gallons used since new on the DIC and my average total mpg since new has been 17.6 mpg. I'am really happy. Happpy Holidays TO ALL. Gene

Hi All and Merry Christmas. Still getting great mileage. Even on winter blend. Still around 19 mpg. Just for the heck of it, I divided the total miles driven by the total gallons used since new on the DIC and my average total mpg since new has been 17.6 mpg. I'am really happy. Happpy Holidays TO ALL. Gene
Don't rub it in :lol: I'm glad your getting great mpg

20 mpg highway 55-65 mph
16-18 mpg mixed country
12-13 mpg stop and go city short trips
12-13 mpg towing 5500 lbs on highway

22,000 on truck and same since day one

I drive around 10 miles in bumper to bumper traffic m-f at an avg of 4mph and only get 12.50-13.00, and it takes 30-45 min to get home thanks to Hurricane Katrina we have new guest from New Orleans, and our traffic is a nightmare-:t

Before the Hurricane it only took 10-15 min to get home !!;)

Hi All and Merry Christmas. Still getting great mileage. Even on winter blend. Still around 19 mpg. Just for the heck of it, I divided the total miles driven by the total gallons used since new on the DIC and my average total mpg since new has been 17.6 mpg. I'am really happy. Happpy Holidays TO ALL. Gene

Can't trust the DIC for MPG or gallons used.

17 last fillup 100% commute here in Phoenix. Usually in the 16s. GPS/hand calc'd.

Can't trust the DIC for MPG or gallons used.

17 last fillup 100% commute here in Phoenix. Usually in the 16s. GPS/hand calc'd.
The DIC is a funny critter, sometimes it seems to be right on the money and other times not:confused: Go figure

It is just an algorithm based on fuel injection and miles traveled. That is why programmer/boxes can effect MPG and gallons used dramatically, however even in stock form, it is no more than a close guesstimate.

1st what is winter blend.i live in florida and took a trip to ohio so do i need to worry about the winter blend. doing about at highway speeds(70) with stock tires i get about 20 - 21 and city i get around 16. and one last thing when should i change my fuel filter especially after my trip. 2005 lly with 11000 miles on it.:grd:

1st what is winter blend.i live in florida and took a trip to ohio so do i need to worry about the winter blend. doing about at highway speeds(70) with stock tires i get about 20 - 21 and city i get around 16. and one last thing when should i change my fuel filter especially after my trip. 2005 lly with 11000 miles on it.:grd:
I guess it depends on where you buy your fuel

I just figured mine out I get 16mpg. Thats 32 miles back and forth to work not much stoping and 2 trips a week to cleveland which is about 80 miles one way.

I am getting 15 empty and 12 towing in Florida. It use to be almost 17 empty but has gone down a little.

I drive around 10 miles in bumper to bumper traffic m-f at an avg of 4mph and only get 12.50-13.00, and it takes 30-45 min to get home thanks to Hurricane Katrina we have new guest from New Orleans, and our traffic is a nightmare-:t

Before the Hurricane it only took 10-15 min to get home !!;)

That is about the kind of mileage I get. I drive about 4 miles each way to and from work, avg speed between lights about 20mph. It takes me about 30 mins in traffic, so I idle alot too. The worst I have gotten is about 9.5, but now at about 20k miles, it is pretty consistant at about 12 to 13. (I also have 285 size tires, so this is and additional drain on the stop & Go traffic mileage numbers) The best I have ever gotten on my truck was 18mpg empty on the freeway, and I average around 10 - 12 towing. Winter blend will also take away from milegae as well.

Bill

Since posting this thread a couple of weeks ago my mpg has gone up. Not sure if it is the weather which is a little warmer and mild or the CRC which makes a diesel additive . Either way I was geting around 10,11 around town now it's 14mpg and that's is mainly city driving .

I bought a 2005 2500HD D/A demo that had 5K miles on it. First thing I did was check tire air pressure. All tires had 42-44 lbs. Rear now has 80 psi and front 55 psi. Over all DIC indicates mpg (total miles/gal used) is 14.7 and with my driving (combo town/hwy) it's getting 17.4 mpg. Underinflated tires will certainly affect mpg.

80 psi in an empty bed? How can that help mpg?

80 psi in an empty bed? How can that help mpg?

hi pressure= low rolling resistance. Rolling resistance is a signficant contributor to overall resistance, only thing bigger is wind resistance which goes up as the square of the speed.

Downside is center tire wear. I found that about 65psi all around is a good compromise. tires wear fine, better mpg.

I bought a 2005 2500HD D/A demo that had 5K miles on it. First thing I did was check tire air pressure. All tires had 42-44 lbs. Rear now has 80 psi and front 55 psi. Over all DIC indicates mpg (total miles/gal used) is 14.7 and with my driving (combo town/hwy) it's getting 17.4 mpg. Underinflated tires will certainly affect mpg.
:exactly: Sometime ago I had under inflated tires and it affected my mpg, put the correct psi in and the mpg improved

The part I don't understand is the 80 psi in the rear. Empty, the front axle carries 2/3rd of the truck. If anything you should have 80 in the front, 50 in the rear, unless you are loaded with 3K in the bed.

I have 315's, optimal wear is at 28-32 psi in the back, 40-45 up front. Granted higher P gets a bit more mpg.

Fully Loaded, those numbers sound right. FWIW, about 20% of the total drag is rolling, the rest is Cd, wind resistance. IOW tires can change economy around 1-3 mpg. But I would guess on an empty truck, on the rear, going from 50 to 80 psi, is almost nothing gained. More rest stops and less traction. Braking is important too.

Just an opinion.

The part I don't understand is the 80 psi in the rear. Empty, the front axle carries 2/3rd of the truck. If anything you should have 80 in the front, 50 in the rear, unless you are loaded with 3K in the bed.

I have 315's, optimal wear is at 28-32 psi in the back, 40-45 up front. Granted higher P gets a bit more mpg.

Fully Loaded, those numbers sound right. FWIW, about 20% of the total drag is rolling, the rest is Cd, wind resistance. IOW tires can change economy around 1-3 mpg. But I would guess on an empty truck, on the rear, going from 50 to 80 psi, is almost nothing gained. More rest stops and less traction. Braking is important too.

Just an opinion.
I agree it sounds goofy and I thought the samething. The service manager
said that is what the tires take and that is what GM recommends.:bounce:

Yep the rear psi is high and the ride is not like 40-50psi, but I bought the truck to tow. Try hitching up a load with 40-50 psi in the rear and see what it does to your tires. I use the truck for rv and utility trailer towing and find it a real pain to air up the rear tires when I hook up to tow. Maybe some guys don't and that's fine. Tire psi will affect your truck's performance. Just for giggles run a tank of diesel with high and low and compare.

Hydroplaning is another tire pressure consideration.

I remember back in 1989, taking out a telephone pole after the start of a summer shower. Rear end was all over the place. Not hydroplaning mind you, just sliding on the slick road. Rear end traction loss (slide) was the cause. Lower pressure might have helped that day.

Just for giggles run a tank of diesel with high and low and compare.

I understand what you are saying with load.

Empty, I challenge you to see an economy advantage between 50 and 80 on the rear only, keeping the front at 60. JMO. No doubt there is difference with load.

Then head on over to the G-pad, and see which is preferable for evasive maneuvering and wet weather handling/stopping.

But you are right, it is a work truck.

I just got mine flashed and average 16- 18 around town and 19-23 on the high way. A hugh inprovment from before the flash.

Why was it reflashed?

Please post before/after part numbers on the service sheet.

I was throwing some codes and they reflashed to fix it.

They told me GM is like nextel, the day after a phone comes out its out dated so i guess GM comes out with updated programs for these truck alot.

I was throwing some codes and they reflashed to fix it.

They told me GM is like nextel, the day after a phone comes out its out dated so i guess GM comes out with updated programs for these truck alot.
What all did you get reflashed to get your mpg up, or did that have anything to do with it:confused:

How did you get your control unit reflashed?

I tow a 6600 pound trailer on a daily basis from job to job. All local city driving and lots of hills. I get 10-12 avg and on the highway 14-17 towing. Empty on the highway last week i got 19. Boy that felt good.

I went to the dealer to get the codes scaned and they reflashed it for me. The service manager said they are reflashing all of them with the new program as they come in.

I went to the dealer to get the codes scaned and they reflashed it for me. The service manager said they are reflashing all of them with the new program as they come in.

Please post your befor/after flash part numbers.

I'm getting about 12.5mpg around town like alot of you. I plan to have the reflash done on my next oil change. Bought my truck Oct'04 and it hasn't been flashed yet, hope this helps.

Went to the dealer the other day and asked them to do a reflash of my truck.The service manager who really seemed to know his job unlike some of the yoyos I met in the past told me my truck didn't need to be reflashed. He checked my truck through the vin # and mine was up to date on the program for the ECM. He also told me when GM has the newest program he would contact me and reflash the truck

I went to the dealer to get the codes scaned and they reflashed it for me. The service manager said they are reflashing all of them with the new program as they come in.
You say new programs as they come in, what new program cuz as I said my dealer said my truck which is a 05 lly already has the up to date program, not sure what new program your guy is talking about