Minecart with ----- not facing actual directions

What I expected to happen:

When the minecart with ----- rotates it would face a consistent direction

 

What actually happened:

 

It faces what seems to be a universal direction not relative to its motion

 

Steps to reproduce:

1) Create a hoop as shown in picture 1 or 2

2) Push the minecart

 

[Images a-d show a single motion of a minecart with chest and its 4 consecutive states]