How to move ball ROLL forward at fixed speed + allow LEFT RIGHT navigation ?

Hi all,

I have an isometric camera, ground (use cube object) and a ball (sphere object). I'm trying to make the ball accelerate to a predefined max velocity AND (and this is the hard part) allow the user to input left/right keys to rotate the ball (to navigate the world).

What i'm ACTUALLY trying to achieve is something that feels like CAR physics, meaning that when the user presses RIGHT/LEFT the ball will turn as if it was a CAR.

I've tried so many solutions and none worked, really frustrated by now :S Its important to mention that i want to achieve this using physics, not moving the transform etc.

Any help will be most appreciated !! I work with C# code (but understand JS as well),

Thanks