A few years ago we went to MSM from Le Harve it was one of the greatest day trips we have ever went on ! But, also, one of the most stressfull ! Yes, 2 1/2 or so hours to get there and 2 1/2 to get back.
Off the ship at 7, first in line to get a rental car at 8. GPS in French ! Got there at 1030 or so, saw everything we could in 3 hours. It
I told my Wife at 130 or so we have to leave. The ship didn't leave until 7, but, the car had to be checked in by 5. Couldn't just leave it in their parking lot.
As stressful as it was, I'd do again in a second ! MSM was AMAZING, hopefully, we can get back there again !!