On the Autostrada it is not unusual for the traffic in the fast lane to be travelling at 150kph (20kph above the limit). The average speed camera system, called Tutor, is controlled from a cental operations room and is not always active in all zones. It does not cover the whole Autostrada network but there a sections covered that have had a high incidence of speed related crashes. Sometimes the sections can be quite long perhaps as much as 50 km with cameras every 5 km or so. Often a warning will be displayed on overhead notification panels when it is in operation. Most are in areas of 130kph limit but some, such as on the curvey sections decending towards Genoa on the A7, are on zones with lower limits such as 80kph.
There is a law in place that would allow the raising of the speed limit to 150kph in sections of 3 lanes, plus a breakdown lane, plus the tutor system. It is up to the Autostrada management to request the increase of the limit but so far none have done so.
I have absolutely no idea whether or not the Italian authorities would pursue a speeding infringment on a UK plated car. From my own experience I know that the Swiss will very quickly and efficiently send a fine to the owner of an Italian plated car
