1. Do not use terms such as "long" and "short" to describe driving stages of your journey, but always refer to specific numbers of hours. All your Italian car-mates may quit on you when they realise that the "short" leg of the journey was the 4-hour stretch (you thought "long" was more like 12...)
2. Be aware that an Italian left in control of the car air conditioning will exhibit strange and inexplicable behavior in the use of that device. For example, the point at which they will turn the air conditioning off will be the same point at which you just start to stop sweating. They will also have difficulty in cooling off the car given their aversion to moving currents of air.