Juat picked up new '12 ECSB with the 6.2.

Have a 1500mi road trip coming up.

Do you guys get better mpg running 87 or 91??

 

I haven't tried 87 yet, just 91 and E85. Hwy mileage with alcohol sucks, about 12.5 mpg. With 91 I've done as good as 18.5.

Enjoy your new rig and let us know how it does!

 

Definately better on 91 or 93 octane. When I had the stock tune, I was getting around 18 on a 500 mile trip running between 70 and 75. With 93 tune, getting a little over 20 same speed, same 500 mile trip.

 

I have experience with 87 and E85 in a 2011 CC 4x4 6.2l, all numbers are off of the trucks MPG display, I reset it for each tank to get independent results and fueled up right before getting on interstate (my old man was incredibly critical of the 6.2L I bought and thought it would do no better than 16hwy mpg so i needed very accurate numbers to shut him up). Only Mod is an AFE stage 2 CAI (never ran the highway with complete stock intake).

e85 - 13.3mpg @ 75mph for 2 hour trip. - Only did trip once, milage was terrible so switched back to regular gas.
87 Octane - 18.8-18.9 mpg @ 75mph for same 2 hour trip. - These numbers are consistent through a few trips on the same stretch of highway during april may (typically best milage times here in MN (lower humidity and temps), lower speed will bring it up to 19-19.2

I am waiting on ARH LTs and full cat back and BB tune. I will repost with new numbers after these mods. Hope this helps ya a bit.

 

Never ran 91 or 93 but i would expect it to bump me past 19.0 mpg. Will run that on the next trip with mods and maybe run 87 on the way home to get a comparison.

 

The best mileage I got with Mods below was 17.9 on a 93 Octane tune @ 72mph (Keep in mind this was conservative on the timing).

Stock was about the same on 93 octane, I never ran 87 in my truck except the tank of full the dealership gave me.

 

If I am nice to it I can do pretty good on the HWY. I noticed a decent increase after the tune.

 

I would get the same results after filling my truck up and a 30 mile trip home from Sams, but i can assure anybody that your mpg hand calculated won't be higher than 19. If it is that is one badass tune.

 

2011 6.2 373's 2wd.
16.5 combined
18.5 high way
13.0 on e85 any way you drive it.

 

That was resetting the computer as soon as I got on the hwy. It was a 50 mile trip with cruise set at 65mph.