People can discuss here for now and I will merge the threads later today. Then if someone in the future is doing a search they will find all the discussion in one place.

“ BMW hasn’t revealed the exact nature of the problem, but claims that it’s only an issue for the police due to the way in which forces operate their vehicles and should therefore not be of concern to most consumers.” In other words, don’t drive your poor quality, hugely expensive, high performance BMW fast or it’ll break.

I read that BMW located exhaust and turbos in the V of V8 engines, which led to overheating of the heads/seals and nearby electronic components when driven at very high speeds (as in police chases).

Another design wheeze to squeeze more power/economy with unintended consequences.

The first comment in the article claims it's the EGR,