We're going to Ireland in October & plan to tour by car. Renting a GPS is very expensive. Would it be advisable to buy & download Ireland road maps and bring my own GPS unit? Also, would the GPS charger work the same in an Irish rental car? Thanx.
Yes. Cheaper to buy the new maps than to rent one form the agency.
Yes. 12V car adapters are the same. No need to buy any special adapters.
Buying a GPS here and taking it with you is less expensive if you don't already have one. If you do need to buy one you might consider looking for one already loaded with the maps you will need. If you already have one you can buy the chip for Ireland.
As you have already been told, the charger will work just fine, no matter what car you use it in. The cars in Ireland are no different than the cars here, except the driver sits on the right side.