I'm showing fuel economy of 14.9 mpg on the first tank for my new Duramax. Around 50 miles of highway @ 72 miles/hour, and the rest in city with 38 miles of towing around 3k. I let it idle some :ro) that Saturday morning while cutting grass as it was around 93 degrees-:t .

I'm curious to see what the second tank will bring. Also looking forward to getting some HWY mileage readings. One thing I know--it will beat the 8.1L I traded for it.

Fueled up at a truck stop, and smiled nearly the entire time. ):h

better than me, I got just under 14 for my first tank of gas, no towing. :(

I have been around 14-15 for the first 1100 miles, about 900 of them highway. Hopefully it improves, my LB7 use to get great mileage.

My 1st tank the lie-o-meter said 15.1, I hand calculated 14.7 -- but I don't know how full the dealer filled the tank (I fill it til I see fuel in the filler neck); that was very little fwy but some nice country roads (50mph type). Second tank is a lot more fwy and the lie-o-meter topped out at 17.8, so I'm looking forward to hand calculating this next fillup... No towing or loads yet...

What did your LB7 average, Snow?

My average for the first 1100 miles so far is a little over 18 mpg with a mix of 60/40 highway/city driving. I'm thrilled. Maybe a Predetor next spring to add another 1-2 mpg. And the HP doesn't hurt either if I would need it. I mainly keep my foot out of it.

Figure 17-18 unloaded freeway 70mph cruise control.

You might scratch out 18-19 at 65mph same conditions.

The 8.1 won't begin to compare.:ro)

My first tank netted me 15.9 mpg hand calculated with mostly city driving and a little highway at 55 mph and under. I'm definitely happy!

Just past 20K on my rig.
The hand mpg is slowly going up from 9k when I bought it. I drive 83-85 mph for 35 miles of freeway to work and pull 16.2 mpg (used to be about 14.7). I will take that, but I have noticed that if i actually drove the speed limit i can pull really close to 20.
I also have to add that during this time i have added the edge/ an intake/ and exhaust...

Mine is a 2wd and I drive pretty easy, got 1800 miles on it so far. 100% city with short highway runs of 5-10 miles. First 2 tanks were 17.--, 3rd 18.1 and my last 16.1. The more hw I think the better it is. pulled a 2500lb boat that last tank as well.

I'm pretty happy with it.

I just got 16.5 first tank. I ran around town and 120 miles to the city. Going to tow a trailer to the coast this weekend. Can't wait to see the results.

I am at 13.9 for my lly w/ 1800 miles. I have been beating on it a lot though. I subscribe to the drive it hard during break in theory.

Get about 20 percent better mileage with the Dmax than the 8.1 I had. Drove the 8.1 with a lighter foot.

17.8 MPG, city/highway combined. LLY, 12,000 miles.

I'm getting around 16.5 city/highway mix. 17-17.5 highway @ 75mph. My "old" 01 got 2-3 mpg better than my 05???? Of course I've only got 12K miles on it. My 01 had 56K at trade-in.

Wow something is definetely different with either driving conditions or the truck. Ive been getting no more than 12 mpg on the truck. All city driving it has less that 400 mile though. No highway at all. Thats Miami traffic for ya!!!!

Im hoping it gets better!!!

New [2500 miles] Crew SLT shortbed 4X4 . 17.5 @ 70 Hiway ,21 @ 55 Hiway , 15 or so around town , 11 with a boat behind me . Banks says I will get 2-3 more with the six gun and speedloader .No intake or exhaust mods. Anybody got one ???

Wow something is definetely different with either driving conditions or the truck. Ive been getting no more than 12 mpg on the truck. All city driving it has less that 400 mile though. No highway at all. Thats Miami traffic for ya!!!!

Im hoping it gets better!!!
I am with you. My truck must have a fuel leak compared to all the mizers chiming in on this thread.....

First 200 miles 17.8 mpg. Mostly around town. Can't complain.:)
Steve

I've had mine for one month now and have put 1500 miles on it.

Normal unloaded freeway driving (with A/C on) @ 75mph is around 14mpg.
Towing about 5000lbs on freeway (with A/C on) @ 60mph is around 17mpg. That 15mph makes a huge difference!

My 1st tank the lie-o-meter said 15.1, I hand calculated 14.7 -- but I don't know how full the dealer filled the tank (I fill it til I see fuel in the filler neck); that was very little fwy but some nice country roads (50mph type). Second tank is a lot more fwy and the lie-o-meter topped out at 17.8, so I'm looking forward to hand calculating this next fillup... No towing or loads yet...

ok, just filled up the second tank and the DIC said 17.1 mpg and I hand calc'ed 17 (actuall 16.983, but we'll round up ;) ). This was with about 70% fwy at 65mph, some canyon climbs (25 - 35mpg up twisty grades) and some around town, but all empty and no towing. I'm pretty happy and hope it still goes up from here.

Man the 05's sure don't get what the 01 and 02 lb7's get.