Yes. Normally, rental companies do not offer insurance for items such as: extras, tires, rims, suspension damaged by potholes or curbs, dents, scratches and cracks on the windshield.
Furthermore, loss of or damage to the vehicle´s key or its documents that was brought on by flooding or any other form of force majeure is not covered.
These elements may vary between rental companies. When you sign the rental agreement and pick up your vehicle, make sure you to check all insurance specifications.