Have noticed the rev counter dancing around by +/- 50 revs at about 1600/1700 revs when cruising. Not noticeable when accelerating through this range. You would think the damping fluid had run out of the gauge except it is only in this rev range. Engine is smooth with no mechanical symptoms to agree with what the needle is doing.

Any ideas anyone?

I don't think you'll nail this tbh mate,

 

My Passat would misfire when cold on warm days, the Insignia does it also every now and again, I think they've got the software to a stage where it's pushing the limits of the fuel to the max,

 

You could check the airfilter housing is sealed ok, a little bit of extra air can upset the expected parameters,

 

If you could post a video it might be beneficial.

Thanks Superbia. Engine is super smooth though, no signs of lumpy running whatsoever. I thought it mght be an electrical issue. Was wondering if anyone else's car has a similar phenomenon (misery loves company and all that).

something similar in this thread, have a look http://www.briskoda.net/forums/topic/314640-wobbly-speedometer-in-cruise/

I'm pretty sure there's no damping fluid in any of the gauges in cars made in at least the last decade - all the needles are moved by stepper motors on the Superb. If you listen carefully while it does the needle sweep when you turn on the ignition you can hear them.

Thanks for replies guys. Right had a closer look at this today (not easy when your driving!) and noticed two things. Firstly the speedo is doing this too as per that other thread (so it's not just my CDO flaring up - hate the way they don't put that in alphabetical order) but only deflecting half as much as the rev counter in my car. Secondly it only happens when feathering the throttle ON/OFF to maintain a steady speed, hence the similar symptoms in cruise control. This is definitely electrical, as the engine is very smooth as previously stated. Didn't realise these were stepper motors. Bah, another case of digital better than analogue nonsense (turntable anyone?). I'm beat. Will mention to dealer when it's in for a steering control module update later in the month.

Well, car at the dealers today and tech agreed that the needle is wobbling and he's seen it before. Reckons it is in the control for the instruments, which I also knew, but there's no fix. So it's not a fault, it's a characteristic (apparently)!

That's the dealer saying "fob off". There's a fix, replace the instrument cluster and see if it changes the behaviour. If the wobble is still there, it's not in the cluster.