I get almost 2 mpg's better with my sc and mds disabled

 

interesting on getting better mpg with it off. I just got 10mpg on my 1st tank

Ill try runing 91 to see if that helps. Cant wait to get a tuner to disable it.

I have it on my Yukon and I also think it is worthless.

 

It's a good feature on a light vehicle with a V8, but to be honest that would basically be a sports car and just like a full size truck, who wants to run on 4 cyls with a sports car?

Maybe a mid size SUV like a Grand Cherokee (unless it's an SRT). But in a full size SUV or a pickup, especially a 4x4, screw the thing...