What ensonique said.
Or (this is rpobably a rehash of that link I posted)
Make your cart.
G0 to scene mode and make a target 1, move the target around as if it is outlining the track. Turn on spline path so you can see the spline that represents the movement of the cart.
Use shift printscrene to take a pic of your spline.
Go to object mode. Import that pic as a reference pic.
Use the spline tool to make your tracks in the same shape as the reference pic.
Extrude them.
Import the new tracks into scene mode.
Import cart.
Place the tracks so they are sumperimposed on your spline path.
Make the target 1 the parent of the cart and the camera.
Make another target 2. Make target 1 the parent of this also.
Set both the camera and the cart to face other. Make this other target 2.
The camera and cart will both follow the tracks exactly.
You use the position of target 2 to determine where they point.
please find rough an8 example attached.
move target 2 (called 2 in scene mode) with the green key pressefd on and you will see the orientation of the cart change.
Boron the moron