How does one purchase on line ferry tickets in advance if he will be using a rental car, thus, not being able to furnish registration/ vehicle data?
Simple. Just recognize that you're dealing with a stupid computer.
Never done it for Sardinia, but do it back and forth to Dover all the time.
For vehicle data; pick something that corresponds to the size of what you'll rent.
For registration/license: put in a couple of 'x's or '999999' -- anything that slaps something into the field.
I don't try to make up something that looks realistic, just in case somebody would accuse me of trying to cheat.
If you don't reserve for a Fiat Punta and show up with a van, you haven't screwed anybody.
Not once has anybody asked me to cough up registration -- just passport.
Thanks Ed
I just tried Rental -small and got away with it. Thanks for the response. We are smarter than computers!