[Slalom4me]

For better understanding, perhaps it would also be helpful to consider the electrical principals at work here as these apply to DC motors.

When the armature of a DC motor is turned by mechanical power it produces electrical power (IOW: the motor becomes a DC generator.)  Placing a resistor in the circuit connected to the windings of the armature creates a "Load".  Energy from the electrical power produced by the `generator' (ie: motor driven by mechanical power) performs work in overcoming the load imposed by the resistor, this work produces heat in the resistor which is dissipated in the form of heat.  The work removes energy from the system (circuit), slowing the armature rotation.

   (For more on this, look into "Counter Electromotive Force" or "Back Electromotive Force")

Like motors, generators (motors turned by mechanical power) vary in characteristics.  An FC-130 from a Scalextric varys from an King EVO3 from NSR.  A given resistance or "load" will have different energy dissipation or "braking effect" on motors according to their characteristics.

For a given motor, when driven like a generator, varying resistance or "load" will increase/decrease "braking effect".

When this resistance is applied in an analog fashion through a fixed resistance or a variable potentiometer set to a particular point, then braking effect is fixed.  It can be changed by swapping resistors or changing position of the pot.

The magic begins when someone conspires to apply resistance digitally, or electronically, if you prefer.

Now there is little difference if all that is accomplished digitally is that the same fixed load or resistance (2) is achieved with the same timing as if it were done in an analog fashion with a physical resistor or potentiometer.

But suppose some bright spark figures out how to ramp up the resistance to a determined level and vary the speed at which the ramping-up occurs (1).  Next suppose they figure out how long to sustain the determined level of resistance (3).  Then suppose they reverse their ramping-up rate to create a variable rate ramping-down effect (4).

Well, by crikey.  Then they'd have something.

Put another way, it might look like this:

2.  BRAKES      Braking strength.
1.  ATTACK      Rate at which the brakes are applied to the level set by the brake strength adjustment.
3.  HOLD          Speed at which the brakes will release.  (Actually, Duration for which brakes will be applied at desired max)
4.  DECAY        Rate at which the brakes will decrease once the HOLD level has been reached. (Rather, after HOLD duration has expired.)

Providing user controls for changing the individual parameters enables racers to tune to suit a particular car's characteristics as these change through an event.  Likewise, controls enable racers to adjust settings to optimize braking control to suit a variety of different cars.