2005 E320CDI S211. I have a frankly bizarre issue with the cockpit audible alert/warning system. On start-up, the car emits the usual audible beep. Then a few seconds later when the engine is up and running it emits a double beep, presumably to notify me that all is well. (Is it a self-diagnostic check it has performed by any chance?) Hopefully that sounds familiar to other owners. However - and this is the bizarre bit - ONLY when driving along the M62 between the M1 and Halifax (in either direction I might add) there is a loud long warning beep of about three or four seconds duration. No dashboard messages or anything accompany this loud beep. After about 20 seconds, it emits the double 'all clear' beep and goes about its business as usual. It might do this two or three times in one journey, but only at this location. I have been along this stretch of the M62 three times in the last four years, and on ALL of those occasions this has happened. I do 20-25k miles each year all over the country, and this happens NOWHERE else. If you think you can help out with this one then I would love to hear what you think!