Follow path Constraint, relative locations for offset objects

Question

i made something like this using follow path constraint on 4 objects and 1 curve.

for my project, i need them to become like this. staying at the center but behaving as if they are still on my curve. something like this gif below:

this may be a noob question but my project depends on your answer :>

Answer 1

One approach, (I don't know whether it's the snappiest, or most controllable)

1. Copy the entire rig, track and trucks
2. On the copy, delete all trucks except the copy of the one you want to remain stationary in world space.. 'Target Truck'... ( red in the illustration )
3. Put a Copy Location constraint on the original track, targeted on 'Target Truck', World space, X,Y and Z, all inverted in the constraint.