Answer
See the diagram.
A moving car cannot remain on a straight, super-icy track that is tilted, because the net force is sideways. The car must be rounding a curve, at just the right speed, so that the horizontal component of its normal force provides the required centripetal force to keep it moving in a curved path of that radius.
Highway and racetrack designers bank the curves for this reason, with the expectation that drivers travel the curve within a fairly narrow range of speeds.
