The path travelled by the vehicle is the line connecting the target points travelled by a specified tracking point on the vehicle. A Tracking Point on the first unit of the vehicle is used when the vehicle is travelling forwards and a point on the last unit when it is reversing. The tracking point is also the point that follows the line in the Follow drive mode.
Note that some of the available tracking points, such as the axles, require you to select Left or Right. With the exception of Driver/Pilot and User Defined Point, the tracking point is assumed to be on the center line of the unit. Note that front tracking points on a front steered vehicle tend to give better results that rear tracking points.
If you want to specify a point offset from the center line, select Offset To The Left or Offset To The Right and specify the offset distance.
If you want to track a particular point on the vehicle, select User Defined Point and enter explicit coordinates. X is measured from the front coupling or, if there is no front coupling, from the front axle, increasing positive towards the back of the unit; and Y is measured positive to the right of the center line.
If you are modelling aircraft using Follow you should set the tracking point to Driver/Pilot or Cockpit if you want to simulate the pilot's eye tracking.