@ReflexRob do you have any videos of what your idle is like?
Agree with yours points, although all cars have problems!
I have recently been looking to find a medium sized petrol hatchback, ~two years old and it's so difficult to find a petrol, N/A car! Most are 1.0-1.4 engines with turbos on them! So far the Mazda with the 2.0 petrol seems the top runner.
As with other manufacturers more and more are going down the direct petrol route which will always cause carbon build up.
Be thankful you don't have an early 2.0 TFSI engine with a timing chain on it :)