I feel the need to create another warning for all tourists that may be as unaware as we were. Apparently, in Sicily, cars rented for tourists are targeted by criminal groups that steal stuff from rented cars, especially Fiat Pandas, which are easy to open for them without any visible damage.
Unfortunately, we didn't know this, and we parked near a beach, left our backpacks with all of our stuff in the locked car. We came back from the beach, and our stuff was just gone. Anything you can do is to report it to the police, but you will not see your stuff anymore. Now we are really fucked without all of our passports and electronics, and we are not even insured for it, so please do not make the same mistake as us.
Actually, do not leave anything in any car ever. We actually came back the second day to try to search for our stuff because they sometimes throw out the backpacks without the valuables inside, but we didn't find anything. You can find a lot of empty bags thrown outside near the road. Also, our AirPods were stolen, and we could monitor their location. A day later, they are already in Senegal. Together with our digital camera, iPad, two AirPods, and three passports and all our belongings. Since we could see the robbers were already in Catania when we came from the beach, we showed it to the police and they didn't do anything. I wouldn't necessarily expect the police to help you in a case like this. Please be careful.
Edit: for all the clever people writing here, we should never ever leave anything in our cars. There is a question: what the fuck are you supposed to do when you are doing a road trip? Maybe you have a camper van and you just have to leave your stuff in the car? Let's say you have your passports and cameras constantly with you, but you still might get robbed of all of your clothes and other stuff because here the thieves have no boundaries.
Another edit: read the reviews of the places where you are going or planning to park. We didn't do that, and after we noticed that the place where we park on Google Maps has at least one review that describes exactly what happened to us. The beach that we went to (Marianelli) has many of these reviews, so always check the reviews, unfortunately. All the stuff was also hidden in the trunk, and it was pretty much in the middle of a nature reserve, so we really did not expect this to happen, but it did.