Just returned from a 2 weeks of traveling by car, mostly in France. Following are some of my learnings from my travels:
Rented a Citroen C4 from Sixt (a German rental company) for 12 days for a family of 4 and luggage. I picked up the car from a Paris suburb and returned it to Charles De Gaulle airport at departure. Unlimited milage. I did end up purchasing the extra insurance at time of pickup (The extra insurance is included in the low price if you use an Amex card, not MC or Visa). I would highly recommend Sixt instead of the American known companies. Interesting note: I requested a manual transmission because it was substantially cheaper. I got an automatic because the representative assumed that since I was American that I would want an Automatic. I settled for the auto at no additional charge as a manual was not available in the size car I needed. Also, don't be afraid to have a diesel car, as they have better fuel milage and the liter price is less than gas. And diesel is readily available. The GPS was an absolute necessity!
Always watch out and leave room for motorcycles! They are allowed to "split" lanes any and every where, and they do!
Tolls are everywhere on the French highways and they aren't cheap. I wish I had gotten an "EZ Pass" or the Liberte as it is known in France or toll transponder equivalent! Based on other posts I read, you can get one at major toll plazas by pulling off to the right and going inside. I can't stress this enough! It seems that almost everyone on the road pays cash and there are usually only a few toll booths that accept cash, causing major backups on the frequent toll plazas. We found some of the toll plazas closer to Paris accepted our "chip & signature" MC/Visa, most toll plazas don't accept MC/Visa and it is clearly labeled on macchine. Close attention must be paid to get into the correct lane that accepts cash. Look for the Euro symbol above the booth as early as you can read them. If paying cash, be sure to have lots of small bills (5,10,20) and lots of 1 & 2 Euro coins. This will save you from collecting all the coins returned when paying a small toll with a large bill. Best to be exact or just over. Note: The coin return is too low to retrieve easily.
We did venture into Switzerland and Germany. Switzerland will cost you roughly 43 Euros upon entering if you don't already have a valid Swiss auto tax sticker (it is valid for a year). We didn't travel much in Switzerland, but we did not encounter any tolls! Had we stayed the French route, we probably would have paid at least that in tolls. We did not have any delays at any of the border crossings, but did see backups coming into Switzerland on our departure.
The speed limit on most of the highways are 130 kph (roughly 81 mph), ! always move right after passing, never stay in a left lane if one to the right is empty. Pass and get to the right. I wish we did that here, it works!