Back in Europe again, France this time

For business/training for 5 weeks. Europe, land of the itty bitty cars. Also, my French is rusty. I had a woman approach me on the train and ask me something, the first half of which I understood, but lost the last part entirely.

I drove through LeMans last time I was here in France two years ago, but I don't know if I'll have time to do any touristing around the work schedule I have. Still, doing redline on the Mulsanne straightaway in a rented tiny Peugeot diesel is an experience I wouldn't mind repeating.

I did miss the Paris train system though, it's nice to be able to travel pretty much anywhere for <20 euro. That was something Ireland didn't have when the fiancee and I went last year, though we did a crosscountry tour so it would've been difficult to manage without renting a car.

Any good automotive things I should see that the SNCF will take me to if I have a spare weekend?