If pods are going faster than 187m/s they have implants, likewise with shuttles if they are going faster than 625m/s they have implants. This assumes navigation 5, but lots of people will only have it trained to 4, or even 3. The values in those cases will be 180 m/s for a pod, 600 m/s for a shuttle, and 173m/s for a pod and 575 for a shuttle.
Anything except for these speed values while autopiloting is gaureteed implants, the higher the speed, the more crazy expensive.
Now go forth and shoot more autopiloting incursion retards.