Just a quick update. I finally got around to buying a can of BG44K and the car does seem to run smoother although it could just be me. I used the can over 2 fill ups (normally fill 40 litres at a time) and have since had one more fill up on shell V-Power (only ever used V-power since owning the car). However this morning, after a really cold night in the UK, I came to start the car this morning and had the light come up on the dash and message pop up on the Idrive. this time the car did not seem to be misfiring like it did last time, but wasn't running smooth. I turned the car off and waiting a few seconds, then restarted with no problems whatsoever.
It does seem to be something to do with the weather, just wondering if anyone else has had the problem with the recent cold snap in the UK?