Follow Path deforming

Hi there,
I am trying to make an model follow a path without deforming. I tried using Curve from the modifiers, Follow Path from constraints, even making an Empty and make it a parent for the model but it didn’t work.

Is there a way to make an model to follow a path without deforming?

select ,object select curve, ctrl p, choose follow path.

I did that, and it did nothing. But Thank you, because you said that, i tried it in a new file, and the problem was that i scaled the curve.

That did nothing, but I figured it out, the problem was that I scaled the curve.

And I have an other question: How can i make a 2 models to follow a path correctly? What I want to do is like a rollercoster

EDIT: Sorry about the duble post… but I waited 1 day for the post just to appear…

I made 2 curves for one path, because it only has one path per curve and i wanted the second car off set. One thing that helps is having the object origin right on the curves first segment. so one car needs to be advanced along its path, not by placing it advanced but by having its own path stat at negative frames.
hope it helps maybe you can private message me and you will not need to wait.
here is a blend file at pastall you just down load hassle free
I duplicated the car/cube and path when both was selected, all at the same time. so I had the exact same car and path parented the same. Then in graph editor, I used the G key and the x key to move it on the time not value.

opps http://www.pasteall.org/blend/33236