It depends.  If you hire a car from a not-at-fault rental agency whose primary business is to loan cars and they have their own fleet of vehicles then yes.  If the primary purpose of business is for smash repairs and your smash reparier is loaning you a car, then no.
We provide car hire excess insurance for licensed rental companies such as Avis, Budget, Europcar, Hertz, Thrifty and Sixt.