I highly recommend using Sixt if you are looking to rent a car in Ireland. I am under 25, so when my partner and I visited, we were rejected from Budget, which led us to have to find another car rental company last minute. Sixt had a car available for us in 15 minutes. Without any advance booking, and with the under-age-25 fee, and 4 days, and returning without a full tank of gas, it cost about 415 euros, which we considered a steal. They were extremely helpful and the staff were lenient when we returned our car a few hours late. The car, which we were able to pick up from this very central location, was in great shape and a perfect size! Thank you Sixt!