We are ending a cruise in Freemantle and would like to rent a car and then drop it off at the Perth airport. Are cars available in Freemantle?

Yes.

Absolutely. Freo is basically a suburb of Perth.

I normally recommend Bayswater, but they don't have a depot at the Perth Airport, so you'll have to go with a major for that option.

FYI - the spelling is Fremantle, which might assist in your search.

Perhaps if you were to search, say, 'car hire fremantle' you might find some useful information (such as a list of car hire places in Fremantle - it immediately returns a list of most of the major companies). You may want to start with this one -

https://www.vroomvroomvroom.com.au/l...emantle/#depot

Also see -

http://www.whatsinport.com/Fremantle.htm

I suspect that there may not be rental car facilities at the port terminal itself so it may be necessary to get a taxi / bus / train to a Fremantle pick-up point.