Just a heads up guys - South wales police have a new set of shiny new BMW 5 series diesels doing the rounds on the m4 between Swansea and Cardiff - Totally unmarked, but you can just make out the light bar on the parcel shelf - and they have been lowered dramatically. They were training on the M4 with them yesterday afternoon (near pencoed) doing high speed boxing in manouvers. Scared the crap out of me when 6 of these things just appeared from no where and surrounded a silver mondeo a couple of cars up.