I would suggest 886 members of the Facebook group is not a small number. Admittedly many may not have the problem ...yet. But they are concerned enough to join.
The problem of the Bi Turbo engine is internal. Corrosion of the internal aluminum of the EGR cooler cannot be down the the way a vehicle is driven. And before you say this is not proven, a number of these coolers have been cut open and the corrosion is available for all to see on the group pages.
Our van, admittedly was an ex-hire one, but serviced regularly as a result. I drove it with care but after 2 years it drank oil at 350mls to a litre, kicking in very suddenly at 86k miles. We struggled on, feeding it with oil, for 12 months before it gave up and went into limp mode on the way up to the North East of England. The only solution was a new base engine last December at a cost of over £7k. As retirees, paid for from savings which we had earmarked for other things and will never get back.
VWUK couldn't have been more UNhelpful.
Both Breeze in Poole and Heritage in Bristol were as supportive, as far as they could be.
Many owners have had oil analysis together with compression tests done and found that the oil contains high quantities of aluminum in the oil. Usually one or two cylinders are excessively worn as well.
I personally think it is only a matter of time before all of these engines fail due the same problem.
If asked, I say avoid them and look at a 140bhp version of the T5. This has a stainless steel EGR and cooler which will not corrode.
Alan
