Hi all unity 3d guys, i am making a racing game in unity 3d, i used unity 3d car tutorial’s alternate physics model as a base to make my game, the only problem is that when my car (Player Car) its steady, i mean when there’s no input from player or any forces applied to that object, it moves a bit on its left, and its really annoying, i thought i could make a script to disable the isKinematic option on the rigidbody component when there’s no input from user, but i am looking for a better solution, please help me 
Thanks, Stefano
I just had a problem like this. It turned out that a parent transform had changed one of the scale values (z) from 1 to 0.9999999.
I may have changed it back to 1 without removing childobjects first and that may have caused the problem.
Anyhow the way I solved the problem was to remove the childobjects from the transform that had changed scale. Then delete that transform (it was an empty gameobject anyway) and make a new empty gameobject and attach the children to that instead.
Note that just removing childobjects then setting scale to 1 where it had changed and then reattaching childobjects to it again did NOT work.