I've read others with Eco automatics behave the same way(downshifting in manual mode on throttle input). The display saying M6 at a stop sign however seems wrong and if you can duplicate maybe your dealer could find a fix. Does your manual mode up shift automatically too? The reason I ask is other GM cars/trucks manual mode works differently than my cruze, where say if you lock M5 or M4 it still automatically shift everything, it will just not shift to gears above what you have it set to.
With my 2012 1LT RS automatic no amount of throttle input in any gear will cause a downshift in manual mode. It will only automatically downshift if your speed/RPM for that given gear drop to low and all gear changes are displayed on the DIC.
With my 2012 1LT RS automatic no amount of throttle input in any gear will cause a downshift in manual mode. It will only automatically downshift if your speed/RPM for that given gear drop to low and all gear changes are displayed on the DIC.