Just because you have the run-of-the-mill uninsured motorist (UM) coverage doesn't mean you'll be totally protected if an uninsured driver crashes into your vehicle. Standard UM coverage pays for bodily injury only. In most cases, your collision coverage will pay your repair bill (and you'll have to pay your collision deductible).

But there is a coverage type called uninsured motorist property-damage (UMPD) that pays for repairs to your vehicle if you are struck by an uninsured or underinsured driver. If you cause an accident yourself, your UMPD does not pay for repairs; you'd need collision to cover that trouble.

Usually UMPD coverage is purchased by drivers who don't have collision coverage. Carrying both UMPD and collision would result in unnecessary redundant coverage, although in a few states, if you have both, your UMPD will pay your collision deductible.

Industry sources say UMPD is not highly sought-after where it's optional because it applies in only narrow cases: If someone else hits you and they are underinsured.

Because UMPD is so narrow, it can also be relatively inexpensive. However, in some states there can be a deductible before UMPD pays — as much as $500! (That's in New Jersey.) In other states, UMPD deductibles they are generally $200 to $250; some states have no UMPD deductible.

According to the Property Casualty Insurers Association of America, UMPD is available in all states. In some states it is required; and in some states UMPD must be offered to you when you purchase your policy but you may reject it in writing. Because of the wide variations, it's important to consult your agent.