Well I turned off Mds off for this last tank of gas. With MDS on I was avg. 19-20 mpg to work with mixed driving. This last tank (MDS off)I babied it and only got 16mpg. I think I'll be keeping MDS on for now on. I've always been curious but at the time gas was still 4.00 a gallon and I didn't want to waste the gas.

I derfinitely need to keep mine on. I drive 700 miles a week. I always wondered what it would be without the MDS on.

I had always wondered too. Now I know.LOL

I've been debating turning mine off. I think I'll just leave it be. A lot of folks on Challenger Z are saying that they saw no real loss of fuel efficiency with it off.

Well I'll tell you my results with it on after I fill back up next week.

I've been debating turning mine off. I think I'll just leave it be. A lot of folks on Challenger Z are saying that they saw no real loss of fuel efficiency with it off.
I got almost 300 miles on a tank with it off