Heinz, Firstly, belated birthday wishes for earlier on in the week.
I also have brake issues, my 2011 +4 has done 11,000km and when you brake reasonably hard from 100kmh+ there is a strong shudder in the front end and I have to release the brakes and reapply with less pressure. It only happens at the higher speed, driving around the streets at 50 - 60kmh there seems to be no issue.
I have yet to remove the wheels and check if the problem is obvious (Pads, discs)or if there is another issue. Tyres are good, and not narrow tyres.
