When you read the full report, both bike were affected at the same time, after refuelling. However, although bought at the same time, both bikes have different mileages.
This does seem to point to a common problem, probably fuel related. How bad can the fuel be over there? A 'trip of a lifetime' turns in to 'the nightmare from hell'. These problems are always worse when the wife's with you.
Although the rings are cracked, the piston doesn't look scored. This leads me to think the crown isn't damaged? Something I'd expect with pre-ignition. I'd suspect overheating. Land Rover had a similar problem with the 4.6 Range Rover running lean on part throttle under load. This lead to the liners coming loose. I know this isn't quite the same thing, but does seem to be heading in the same direction.
Before everyone gets carried away, and shoots BMW, lets see what they actually have to say.
I'm not BMW's biggest fan at the moment with 2 out of warranty experiences that didn't go too well, despite extended warranty! However, I would like to see their response before I 'shoot them'.
Hopefully we'll get their response soon.