Civitavecchia

I have done my homework but am unable to find anything in the archives or on the web in general about public transportation in Civitavecchia. We are taking the train from Rome and renting a car in C. From there we go to Tarquinia and beyond. Is it possible to take a bus or metro to the rental agency or do I need to get a taxi? Walking directions on google says there are few walkways or sidwalks between the station and the rental office. Thanks for any help. We'll be in Rome in two weeks!