When renting a car, one has a choice of whether or not to purchase the coverage offered by the rental agency. Unfortunately, like so many other things in life, there is no right answer to this question. Here are a few things to consider:
If you do not have both Collision and Comprehensive/Other-than-Collison coverage on your current policy purchasing the coverage from the rental agency probably makes sense since it would be the only coverage you would have in the event of an accident.
Policies with those coverages would usually give coverage for a rental car, however there could be what is called a “gap” in coverage which is an expense that is not covered. For example, rental contract often contain a charge for “diminuation in value” which is a way of reconizing that a repaired vehicle isn’t worth the same as it would have been before the damage. This coverage is not normally provided by one’s personal auto policy. Since rental cars tend to be less than 1 year old totalling one could be a serious expense. The rental contract could also require additional fees that the auto policy would not necessarily cover.
In the end, you would need to weigh the cost of the rental agency coverage with the risk you are taking without it.