3.0 duramax
 

I just did a long tow , 6000 miles round trip. South Florida to Atlanta and then to San Diego. 21.3 mpg towing a 22 Donzi Classic. Fuel tank was close to full. That was on the way out and I took state roads or fm roads until Tucson and then 10 to the 8. On the way back a storm was coming and I ran north on 15 to St.George Utah and then went south through Page Az and picked up 40 outside of flagstaff. Return trip was 20.4 mpg . Wanted to share the excellent fuel economy. Now the def is a different story. Towing uses a lot more and I went through 7.5 gallons.

thats awesome! 21mpg towing! i can barely squeeze that out of my gasser truck on cruise control on flat land empty!!
What truck? SUV or pickup?

our AT4 got 30-37 going to pa for NHRA this weekend the engine is so impressive i,m trying to buy 2 for a Viking repower project it comes alive when towing like a tractor puller i just found the boost spec on it ........almost 45 pounds no wonder it act like a tractor puller! awesome engine

Chevy Silverado crew cab , high country. 2 wheel drive
https://cimg3.ibsrv.net/gimg/www.off...3c6c9a176.jpeg

Return trip
https://cimg6.ibsrv.net/gimg/www.off...1d6dace26.jpeg

Those are impressive numbers while towing. Id be interested to see hand calculated numbers to compare to the trucks system.

for those that have a 21 3.0 theres a computer update to fix turning over but no start issue

Onboard vehicle MPG calculations are notoriously inaccurate. Did you do the long math?

exactly. I always hand calculate my fuel mileage.

Me to,,,,,,,, only way to do it on my 1996! LOL

I've yet to own a truck (or car for that matter) that the computer calculated MPG wasn't to the happy side.

Also purchased a 1500 3.0L this year, gas millage is awesome, and towing has been pretty impressive thus far too. Recently hauled a 30' cat and felt great power wise.

Yeah , so far so good ! I didn’t do the math on my fuel economy , even at 10 percent it’s still pretty darn good. I towed 2 years earlier in a 2018 Silverado 5.3 gas out to Powell. 14.5 on the dic. And on that tow I took major interstates as much as possible. This last time out to Ca. I didn’t get on an interstate until a little east of Tucson. Stress free on state roads and FM roads.