If you find yourself in a specific Branch Office and enter
Car > All Cars
You will see the availability of cars of that specific Branch Office
Example if you are at the "Los Angeles" Branch Office, you will see the availability of cars of Los Angeles (as you can see in the image below)
But in case you need to see the availability of all cars from all the Branch Offices you will have to click on the Branch Office filter, and press on the cross, in order to eliminate the filter and be able to see the availability of all cars from all branch offices.
You can now see all the cars from all the Branch Offices.