Originally Posted by brad12kx
ECO and MDS are not the same thing and are only partially related. ECO is just an indication that you are driving in what some programmer considered to be an economical fashion, and suggests that you are getting pretty good fuel mileage.
MDS will only kick in when the load on the engine is low enough for the 4 cylinder operation to maintain the vehicle speed without over fueling.
Partial relationship -
You can be in ECO mode without MDS....but not the other way.
In order for the MDS to kick in, you must already be driving in 'ECO' mode.
I follow the way you think it works, except, what do you mean by "over fueling"?