Smoothing out my MM and MMM

[Big House]

I made an observation the other day. i finally got one of my other models back together and I have an Associated Brushed speed control in it. At the slightest application of throttle input the car moves as smooth as silk.

Now in contrast, I have 2 MM and 1 MMM and as powerful as they are and as reliable as they are, why can they be as smooth as the assoicated comtroller. Mind you I am not getting rid of any of them, but I would just like some insight into this little issue.