I drove up to MD and back for the Pontiac Outlaw Nationals race at Cecil County Dragway. I put some Lucas Fuel additive in before each fillup looking for better MPG. Traveled 1423 miles, burning 104.8 gallons for a final MPG figure of 13.5, towing my racecar on an open trailer. 72 MPH most of the time except when I had to go slower.

I dont think the additive made a bit of difference.

Its a great truck on the freeway, no complaints...

Sounds about right. Did you think you would see a big improvment? What was your towing mileage before trying the additive?? A freer flowing exhaust may help. But for going 72 that is really not that bad. I bet if you kept your rpm's below 1900 you would get better. Stock tires???

Its been getting around 12-13 MPG towing since new. Its hard to go 60 MPH when everything else on the highway is doing 75+.
Its got stock tires, its all stock but the items in my signature. I now have 23,000 miles on as well, I hear the diesels take a while to break-in. I guess another 1-2 MPG would make me happier.

Its a great truck, dont get me wrong, tons of towing power in the Duramax allison package.

I hear what your saying. I tow about an 8k travel trailer and get maybe 12mpg if I'm lucky.

I know it's hard to drive 60 especially when you want to get there. I keep thinking if I do this or do that it will get better. I've found the best method for getting good mileage towing is to either drive all down hill or lie about it):h

I'm usually not too happy about fuel mileage on my LLY. I did just complete a 1000 mile tow of my 7000# trailer. Averaged 14.2 MPG, that made me happy. I averaged about 65 or so, I like to keep the trailer under 70 unless I'm passing. I did notice a 1 MPG increase when running a tank of B5

...oh yea all hand calculated and tire corrected

I got 8.5 pulling my 5th to colorado, got 4.5 coming back but it was @30mph winds. Still sucks tho. I never see north of 9mpg anymore and dont know why.