I have had my truck for about a year and my fuel mileage around town averages 12.5. On the road at 75 mph I am only getting 14.5. If I drive 65 it will go up to 16. I thought that the milega would be better than that. Most of the people I have talked with are getting 2-3 mgg's better. Any suggestions on where to start or is this what I should expect?

seems low to me... have almost the exact same truck and I get around 18 fwy when not running a programmer and around 20-21 fwy when running hypertech progammer. I recommend getting a programmer that will help with mileage, but it sounds like you have another problem. Simple solutions which you might have already done is check your tire pressure and also your air filter to see if it is clogged.

that sounds a little low

Fwiw, my readout says I'm averaging about 15.5 which is highway/city, up to 80mph at times, as low as 60mph, and 315/75/16 tires

You should be getting better than that, I get 16 city and 22 on trips on a 2 wheel drive short bed on my 03 LB7.

that does seem a little low, but there's also a lot of variables that need to be considered. Temperature, wind, fuel quality, alignment, tires and tire tread....etc. Just not enough details here.

Have you changed your fuel filter lately? If it is restricted, your mileage will go to s**t.

seems low to me... have almost the exact same truck and I get around 18 fwy when not running a programmer and around 20-21 fwy when running hypertech progammer. I recommend getting a programmer that will help with mileage, but it sounds like you have another problem. Simple solutions which you might have already done is check your tire pressure and also your air filter to see if it is clogged.

Ditto

little low to me. I am getting a true 19.8 all around with 315s. In dash say 22.4 but the trusty calculator says different. Juice seems to really help in the mileage mode.

are you a dually? in the winter i only get about 18 because of sinter fuel. this is solid interstate driving. i agree about checking the air filter/ fuel filter first. wil

Just calculated mine yesterday...... 17.9 (in town and highway driving)

I got 19.6 on my last tank.

Must be nice, I get 12.5. I've learned to just deal with it, I've tried everything humanly possible and it hasn't worked yet. Still sh!++y. :(

It's your tires. I had the same problem for 60k running 285's. I recently went to 265'5 and my mileage jumped to 19+ at 75mph. Are you also compensating for the larger tire in your calc by multiplying your miles by 1.078 (the dfference between stock and 285's), then dividing by gallons used. If not, your mileage calc is low by 7.8%. I'll never run 285's again.

It's your tires. I had the same problem for 60k running 285's. I recently went to 265'5 and my mileage jumped to 19+ at 75mph. Are you also compensating for the larger tire in your calc by multiplying your miles by 1.078 (the dfference between stock and 285's), then dividing by gallons used. If not, your mileage calc is low by 7.8%. I'll never run 285's again.

Well, at least on mine the poor mileage started long before the 285's. Plus the speedo has been reprogrammed. I've already been through the dealer many times and they can't find nothing wrong. When I first got my truck 2 years ago(used), the first time I checked the mileage it was just at 19mpg. Haven't hit it since.

I'm getting 17 mpg city and 20-21 mpg highway. Stock rims with 245's and a canopy. Not sure if the canopy helps the mileage though.
Also have a BD programmer on level 2.

I run 305/70/16's and my Banks on level 3 and usually get 16-17 running 70-80mph if I drop the speed to 65-70 I get around 18-20, if I drop the speed to 55-60 I get over 20. no matter what these are big heavy trucks, it takes alot of fuel to keep them going, up even small rises.aerodynamic resistance increases exponentially as you go faster, thats most of the difference in mileage at various speeds. IE: my little olds alero gets 25mpg running 90, and a corvette c5 gets 30mpg on the highway running 80, because aerodynamic resistance is low. A shell or tonneau will help for sure, but not much so don't buy one just for mileage. just my 2 cents

Fuel Filter sounds like the most logical place to start. What is the best chip or programmer to use for fuel mileage?

I lived in Florida (flat land ) 18.3 MPG. Now I live in Delaware where it is hilly my mileage drop to 16.7 MPG. Here in Delaware I'm using Standyne and also Amsoil Cetane Booser. I noticed the hills here are small but the fuel mileage drop down.

I get 15.5 to 16 around town and 16.5 to 17 hwy fuel filter was just changed and I have a K&N air filter (clean) with a diablo III programmer set on standard tune along with 285s. Wish I would get up in the 20s on the hwy

I have 17.53 mpg since new. That is with towing 8k about 35% of the miles. Drive like an old lady, drop the tire size back to stock, don't idle to warm it up and keep the speed at 65-68 mph.

I really feeeel that the Chevy engineers have the computer programed to give optimum performance with the stock tires and the larger 285's kick it into a power mode that wastes fuel when driving empty. Who knows for sure?

jb

My 04 has 285's with a Hypertech programmer set on level 1 and a roll-n-lock bed cover. I get 16-17 mpg around town and 18-19 on the highway via hand calc. I get 12 towing a 5000 lbs boat. My gas mileage directly correlates to how heavy my right foot is... :)

i had a 03 crew cab short box dmax and it got 22 to26 miles per imperial gallon. if you want good milage keep your speed down to 55 max, that way you run about 1600 to1800 rpm. thats the sweet spot for a diesel engine the more r's you give them the more fuel you burn.

Buy a programmer and put in economy-tow program period!

Must be nice, I get 12.5. I've learned to just deal with it, I've tried everything humanly possible and it hasn't worked yet. Still sh!++y. :(

Man I feel your pains. :confused: I bought my truck simply for the fuel mileage and towing power. Everyone told my by a diesel, everything I read said go diesel. I get 16 MPG max in city/highway driving empty and 7-10MPG towing trying to maintain 65mph. Unless I am calculating wrong I've seen 18mpg one time and that was the first tank after my injectors were replaced about a month ago. Since then it is back to 16MPG. I have not pulled anything yet. I do have the Edge juice w/attitude and love the extra throttle response. I run in level 1 with the low boost set at level3. These settings are for fuel economy but I have not noticed a different. My truck is totally stock with the exception of the juice. This is how I calculate MPG: I fill the tank, zero the trip ometer, drive easy, refill tank, divide the mileage by the number of gallons used. I have done everything that was suggested by the guys on this forum. The best thing I can offer that did help is have you injectors changed. I drive an 02 LB7 w/105,000 miles on it. I Love the truck but I have had more problems with it than any other Chevy I have owned.
Good Luck.

I'm feeling bad for you guys..... on summer diesel I get 20 (US) doing 70mph... city is closer to 16.

I hear there is a good EFIlive economy tune... i wonder if it will help the thirsty truck proportionally more... i.e. bring it back to standard and beyond in terms of fuel economy.