I am planning a trip with 2 cousins in late May. hope to fly to Edinburgh and stay 2 nights. then either take train to Inverness and do day tours or rent a car for Skye and Culloden. What I haven't been able to tell from the Rick Steves guide (which I am enjoying) is- are there car rental places by the Ferry terminals to drop off car in Scotland and then rent in Ireland? (I took this route as part of a tour in 2016 but didn't notice)... Other advice that I have seen is not to take the rental on the ferry as we plan to fly home from Shannon. Has anyone taken this route? thank you.
I haven't taken the ferries, but the advice not to take the car across is partly because you're changing countries -- unless you want to take the ferry to Belfast. In that case you'd still be in the UK, but since your end point is Shannon you'll still be returning the car in a different country.
As you plan to go to the northern part of Scotland after Edinburgh, you'll not be near the ferry terminal (unless I'm very misinformed, which is always possible). The main ferry to Northern Ireland leaves from Cairnryan, about 80 miles southwest of Glasgow. There's also a seasonal ferry from Cambeltown, but that is way, way at the end of the Argyll & Kintyre peninsula, just as far from where you'll be in Scotland. If you want a ferry to Republic of Ireland, you'll be going out of Wales and landing in Rosslare, near Wexford.
Google Maps shows a Hertz office (only) at the Cairnryan Stena Line Terminal.
How about flying from Inverness to Belfast, I looked on Expedia and next May there is a daily flight on Flybe at a low price. There is also a daily flight to Shannon from Edinburgh and several from Edinburgh to Dublin. I am not sure where you want to start your Irish tour but flying may be quicker and cheaper than travelling by ferry and may also resolve any car rental problem.
We had considered ferrying across from Scotland to Ireland (or vice versa) on our upcoming June trip, but decided against it for the following reasons:
1. Car Rental companies don't appear to appreciate renting in UK and taking the car to Ireland to continue driving it.
2. Drop-off sites/pick-up rentals near Ferry Terminals in Scotland - I was unsure if drop-off fee would be greater since it would be a one-way drop-off. Read something yesterday on Rick Steves that that is apparently not an issue in parts of Europe. Still don't know about Scotland. Do know that if you are picking up a car at a smaller city/town, your choice of rental car size/tech package will be more limited than if you rent in Glasgow or Edinburg.
3. The ferry trip is long. Scenic, I imagine, but long (I'm a sailor and am always drawn to the sea, but when I have limited time to see two countries, I'd rather spend the time seeing the country rather than on a long ferry ride - others may feel differently and I respect that!). Flights from Edinburg to Dublin are cheap - cheaper than ferry when you consider car drop-off hassles, and shorter than ferry ride.
4. Suffice to say that even though we are flying from USA to Dublin, we are then catching a flight to Edinburg later that day and will fly back to Dublin to then tour parts of Ireland before flying home. Others may have more practical experience/wisdom so hopefully they will share. Have a super trip!