(a) A policy that grants the coverage required for a motor vehicle liability policy may also grant lawful coverage in excess of or in addition to the coverage specified for a policy and the excess or additional coverage is not subject to the provisions of this chapter. With respect to a policy that grants excess or additional coverage, the term “motor vehicle liability policy” applies only to that part of the coverage that is required by this chapter.
(b) A policy is excluded from the application of this chapter if the automobile or motor vehicle liability coverage is provided only on an excess or umbrella basis.