What to do with luggage while visiting Chartres

I have left luggage in rental car trunks on dozens and dozens of occasions, across Italy, Germany and France (including Chartres). I have never had an issue, but no one can categorically promise that you will not have an issue!

One thing I am very meticulous about is NOT opening the trunk at the place I intend to park. We make sure we have anything we need inside the car, including passports, credit cards, valuables etc. That way, when we park, we can simply get out of the car and walk off. There is no possibility that someone hanging around will see us open a trunk full of cases. Similarly, we leave absolutely nothing in the car (not even the phone charger as someone may think there is a phone hidden in the car).

The advice above is good. It is critical not to open and be fishing around in the trunk when you stop. It is also IMHO critical that your cameras, computers, ID, prescription drugs and other valuables are carried with you. I know someone who had everything stolen from their trunk on a holiday -- they lost all their clothes but worse their meds which was tricky to replace. So it is always a risk; you won't know if the place you park is a target for a group of thieves (we never leave luggage in a car at a beach stop since those seem to be particular targets); diminish the risk to your underwear and jeans not your computer and camera etc. It is kind of a pain but we each have a messenger bag that holds our valuables and lug that into lunch or a museum visit or Cathedral on the way.

And nothing left in the car. No jacket, book, phone jack etc -- nothing should show outside when someone looks in.

Thanks for the advice. The last couple of times we've been so called "upgraded" to an estate car (station wagon) so the baggage is difficult to conceal. I'll insist on a sedan with a trunk.

Unfortunately in Europe it is very difficult to get sedans when you rent. Most of the cars are hatchbacks. Those do have covers and so offer routine coverage of luggage, but they make me nervous. The very fact that the cover is pulled suggests that goodies lie below. I would not risk it in a station wagon where the luggage is sitting visible.