Only if the repair is going to take more than a day you can get a rental car, that you must be able to meet the requirements to get. I.e. Valid Drivers license, Credit Card, Etc.
If they know they won't need it overnight you'll be hard pressed to get a rental. Now, if it is getting late and they still haven't fixed it, and you are going to be without a vehicle, tell them you want the Rental Provided.
Good luck.