Physics of Car Driving on Banked Curve: Forces at Play

[Melac12]

When a car drives on a banked curve it pushes into the ground and the ground pushes back making its normal force bigger then it would be just form the perpendicular component (to the road) of gravity. And at a perfect speed, the normal force’s up component balances the gravity. My first question is what about the component of gravity parallel to the road. I know that we don’t use a tilted coordinate system but that component of gravity has to do something, and since in other cases when the speed is not perfect the force of friction either acts up or down parallel to the road. Clearly the force of friction is not affected by gravity in any way. So what happens to the parallel part of gravity, or at least why is it not an issue?
http://batesvilleinschools.com/physics/PhyNet/Mechanics/Circular%20Motion/banked_with_friction.htm

 

[haruspex]

at a perfect speed, the normal force’s up component balances the gravity.

Quite so, but the perpendicular direction to that is horizontal, not parallel to the road surface.
In the parallel to road direction, you have a component of gravity and no normal force, so there is an acceleration. This will be the component of the centripetal acceleration in that direction.