Our son went away to college and when he wanted to rent a vehicle, the rental company would only rent to him if our auto policy would cover him.

A child at school away from the parents' home is still considered a family member in most instances. There may be special circumstances that negate this point, but, in general, a college student fits the definition of family member as defined on the auto policy. However, there are exclusions on the auto policy to consider if the son is going to rent a car while at school.

There is no liability coverage for the use of any vehicle, other than your own "covered auto," that is furnished or available for the regular use of any family member. So, if your son is renting a vehicle, that is a vehicle furnished for his regular use, and it is not included in the definition of your "covered auto." The exclusion would prevent liability coverage for your son.

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As for physical-damage coverage, the car insurance policy does provide such coverage for nonowned autos, but in this case, your son would not have that either. Nonowned autos are defined as "autos not owned by or furnished or available for the regular use of the named insured or any family member." If your son is renting a car that is going to be available for his regular use, it does not fit the definition of a nonowned auto.

If the rental is just a short-term rental, for a weekend or even one week, that changes the dynamics and the exclusions are not going to apply; he'll be covered for a short-term rental. But if your son is involved in long-term rentals, your auto insurance policy will not provide the insurance coverage he needs even though he is considered a family member under your policy.