Hi All, this is an intermittent problem that I have know about for the past couple of years but never really gotten around to investigating it. 
 

I have a 2011 S-Line with the 3.0 TDI engine, manual gearbox. It’s just north of 90,000 miles. There is the strange feeling sometimes when coming to a stop, usually after driving for a bit when the engine is fully up to temperature. I will be at a red light waiting, in neutral with the parking brake on and I will feel the car beneath me moving sporadically, this movement also coincides with either a drop or a rise in RPM, albeit very slight.

It has just happened now after i drove about 60 miles and had parked up, I was able to take a video showing the movement to the needle, if anyone has any idea what could possibly be causing it and if its cause for concern I would love to know. 

I’ve been finding little thing recently that are honestly making me consider getting a new car, but when I got this on 2021 the whole reason I bought it was because it was a low mileage diesel with, what I assumed to be a lot of life left in it, but now I’m not too sure 😞
 

Please let me know your thoughts. 

I suspect the engine is misfiring a little at idle then over-recovering causing its balance to change briefly. The possible causes are myriad so it would be worth getting it professionally scanned or use a VAG compliant code reader.

It could be an issue with the injector or injector seal. If it's an injector they can be tested. 

But I'd recommend a diagnostic check to see if any fault codes flag up.