a
mechanical speed control is actually more efficient then an
ESC as far as main
battery consumption. the
ESC's true
advantage is that it's use kills
the need for the
mechanical speed control's
servo and the
receiver's pack of 4
AA batteries.
that is a significant amount of
weight to shed for a racing
R/C car.
also, there are no moving part in an
electronic speed control, so it doesn't need the constant cleaning that a
mechanical speed control does.