Paris to Rouen with stop in Giverny

Couple of issues. You would need separate tickets. Paris to Vernon, and Vernon to Rouen.

There is no luggage storage at the Vernon train station.

If picking up a rental car on Sunday, make sure the rental office is open. Most rental agencies other than at airports, are closed on Sundays.

Make sure you know the hours for car rental pick up on Sunday. We left Rouen on a Sunday and drove to Lille, but had to time the car return in Lille within the same hour as our train departure to Ghent because hours are pretty limited on Sundays. It all worked out, but I was not sure how it was going to play out.

Also, are you staying in Rouen. It's very pedestrian friendly, but not very car friendly? Lots of traffic and no place to park. I would suggest waiting until day of departure from Rouen if that isn't already the case. However, if you are leaving Rouen on that Sunday at least you'll avoid rush hour workday traffic.

Thank you. Great advice-I hadn’t considered luggage storage!

I might add, originally we looked into picking up a car in Mantes la-Jolie which is a few stops prior to Vernon/Giverny; as it looked like it had decent options for car rentals. Since you need luggage storage to visit Giverny perhaps that might be a solution; if you feel comfortable leaving luggage in the trunk of the car. Of course, there's the Sunday factor as well, but it might be worth looking into.

We ended up going to Brittany first, so we didn't follow through with Mantes la-Jolie, but you may want to consider that option.

Also, remember to pick up your International Driving Permit at your local AAA office before you depart the US. (No membership required.) We were asked for it by the car rental agency.

Thank you! I’ll look into that as well as Sunday car rental hours.

Sunday car rental hours

Those are limited, and I would be surprised if Mantes-La-Jolie car rental offices were open on Sundays at all.
Thankfully, traffic is really light in the Paris area on a Sunday morning, so you could just pick up the car in Paris (ideally near Porte Maillot) and drive away on the A14 and A13. No issues finding an open car rental office in Paris on a Sunday.

Car rentals outside airports do keep limited hours. They also often take a long lunch. WE found that in Caen. So be very sure your agency is open when you need it. I would not want to plan a Sunday pick up or noonish pick up without knowing for sure the agency was open.