We are driving throughout Portugal for a month in September 2018. We will be renting a car from Avis in Lisbon. Is it possible to pay tolls on the toll roads (i.e. A8) using a credit card (i.e. AMEX or VISA), or can we use a pre paid card? Or is it necessary or desirable to purchase a transponder with the rental from Avis?
Thank you for your assistance.