the whole cogging effect has been worked on for a long time. the timing of the coil to the nuetral plane requires feedback(sensors). the more feedback the smoother it could be.

every time a coil pulls or pushes on a pole there is an acceleration and deceleration rate. the pole is attracted or repulsed from the coil and the current and rotor strength work against each other. cogging comes from this.

you can dampen these micro accelerations by adding weight to the rotor. you are adding to the inertia of the rotor. you can also gear the car so that the gear train dampens these micro accelerations. a 3:1 gear ratio will dampen the motor more than a 4:1.