It works fine in the Ram at speeds of 55 or less. Since most hwys are now 65 to 70, the MDS tuning doesn't allow it to stay engaged long enough to do any good at those speeds unless the road is completely flat. The Ram is a brick in the wind and on an incline, it won't stay engaged enough to do any good. On flat land, I have gotten 24mpg @ 60mph, but I drive 70 on hilly interstate daily and get around 18 to 19 with the mds turned off.

 

When I get my tuner, my MDS will definitely be turned off. Worthless.

 

Add me to the list of guys that think the MDS system is worthless on the Ram. My 07 Hemi 4X4 Quad nets me about 15 to 16mpg, and I drive a lot of expressway. My custom Magnaflow exhaust allows me to easily hear it kicking in and out, which seems excessive. With the problems I have already had with this truck, I worry about what might wear out with the MDS system in place, versus just a simple eight cylinder engine running normal all the time.

 

Glad I don't have it, it would be turned off if I did.

A pretty good friend of mine has a Grand Cherokee with a Hemi, MDS and it does pretty good on gas, better than my '02 Grand Cherokee with the 4.7 HO in it, despite the fact that hers has a larger engine and the WK GCs are a good bit heavier than the WJs...

 

Hammer-

I think there is a programmer in my Ram's future.

 

MDS sucks...period!

 

I think the MDS can help mileage in some ways but it is not good for performance and power

 

It works better on the lighter cars like the Charger, Challenger, etc. it kicks in and out so much on the trucks at speeds over 60 that it is got to be hard on the trans lockup solenoid because when the MDS kicks in, the lockup clutch releases 30% and the rpms go up about 300rpm. it is very annoying and can't be good for the transmission.
The 09-up have a more aggressive mds tune that holds it in longer. This might be possible because of the variable intake runners and VVT. It nets me about .5mpg with it on, but due to the on/off cycling, I just turn it off.