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OK so the BlueGT has the ACT cylinder deactivation feature.

It is advertised that it switches between 2 and 4 cylinder modes imperceptibly.

When it drops from 4 to 2 cylinder mode, agreed it is not really obvious.

When in 2 cylinder mode, mine is struggling in some conditions often on level ground at low to medium speeds like 30 to 50MPH, you can hear it makes something like the old knocking/pinking sound and then give it a little press of the throttle, then it switches back to 4 cylinder mode. And the knocking/pinking noise stops immediately.

So is the switching truly imperceptible for others? OK so Yes if I have the radio on at normal levels, it is hard to hear it.

Sometimes I find the DSG has got itself into a very high gear, usually 7th, and the ACT turns off because the revs are low for the current speed in that high gear, blip the gears down to 6th, the revs climb a little so the cylinders deactivate and presto better MPG!

What do others think?

Personally I have never noticed any sounds, vibrations or anything else on the ACT - but I don't ever drive without the radio on.

And yes, the DSG does often end up in a gear where the ACT cannot be activated - I just ignore it as it only really happens to me at 30mph in 5th, and I am lucky enough to spend very little time in urban driving. I can imagine it might be annoying in city driving etc.

Given that there is a knock sensor you should not get any pinking. The car should return to four cylinder mode before it struggles. I recognise none of your symptoms and yes I do find the change over imperceptible either audibly or through vibration or harshness. It sounds as though your car is a bit off colour.

I know what you mean. Mine doesn't make too much noise when in 2CM, but it feels a bit like driving in 6th gear at 20mph; rough and a bit juddery. I guess this is the price to pay for being early adopters.

Ah Frog, I think we are seeing and hearing the same thing, agreed it the sound is like going too slow in too high a gear.

I am going to take it to VW for a look at. I have owned the car since October and noticed these things fairly quickly, but I have held off until now while just trying to rule out anything to do with my driving style as being the cause.

On fuel consumption, while other have stated they achieve the 60MPG (combined cycle) figure easily I have not found that. Last night on the way home on a 20 odd mile stretch of motorway which was not totally level, I set the cruise control at a speed which kept the revs to about 2000rpm, so somewhere between 65-70MPH. This helped a great deal, I need to do this a few times in the next few weeks to see if the results are consistent, what I saw was encouraging that better MPG may be possible.

pzboyz wrote:Ah Frog, I think we are seeing and hearing the same thing, agreed it the sound is like going too slow in too high a gear.

I am going to take it to VW for a look at. I have owned the car since October and noticed these things fairly quickly, but I have held off until now while just trying to rule out anything to do with my driving style as being the cause.

I would be interested in what VW say, I had assumed the slight juddering/vibration was normal. TBH, I only really notice it when the engine is under a slight load, like on an incline, for example, just before it 'gives in' and goes back to 4 cylinders.

I have a BGT with 16000km.

Ed