Custom Cart System curve help

I am making a custom rail / cart system. You can place your own rails and then place your own cart to ride in it.

Rail system(using egomoose’s furniture placement system):

And my custom cart(Similar to the normal cart ride into… games cart):

The cart works fine, but im struggling to make it go around corners.
In the picture you can see white rectangles on each side of the cart, they will be invisible.

The curves look like this:

When i try to use it this happends:

The cart is using BodyVelocity, BodyForce and BodyGyro (copied from the free model cart).
Any ideas to make it turn around the corners?

The best way to do this is to use the TweenService. Look at the script from this tutorial:
How to Make a MINECART | HowToRoblox - YouTube.