Part D (Coverage for Damage to Your Auto) pays for direct and accidental loss to the insured's own auto. It has two coverages: - Collision: upset of the auto or its impact with another vehicle or object, such as a pole or guardrail. - Other Than Collision (OTC): ISO's newer name for what many insurers still call comprehensive. It covers causes such as theft, fire, hail and contact with a bird or animal. The CDI outline stresses that OTC is a type of property insurance on the insured's own auto. Liability coverage, and California's financial responsibility limits, deal with damage done to others.

Sorting losses: a driver who swerves to avoid a deer, never touches it, and hits a guardrail has a collision loss, not an OTC loss, so it is not covered if she bought only OTC. A thief who breaks a window to steal from the car causes an OTC glass loss.

What Part D does not cover: damage due and confined to wear and tear or to mechanical or electrical breakdown, because those are expected maintenance costs. Personal effects carried in the auto, such as a suitcase or golf clubs, are not part of the auto; the owner looks to a homeowners or renters policy or an optional endorsement.

Deductibles: when two covered autos on the same policy are damaged in the same collision, only the highest applicable deductible applies. Example: Car A ($500 deductible, $3,000 of damage) backs into Car B ($1,000 deductible, $4,000 of damage). The insurer pays $7,000 − $1,000 = $6,000, not $5,500.