Hi and welcome
Rear lights cracking and filling with water. Other than that I had 30K happy miles and 2 years from it with No other issues unlike the old E85's niggles and leaks.
I would look at extending the warty from BMW if you can, mine was £39.99 with except disks and clutch with £100 excess.
MPG expect 26 to 31.
Check service needs as its complicated (I have posted today on this).
I dumped the 30i early due to the petrol and enjoying the 28i and saving over £100 in terms of petrol, insurance, tax, inclusive service and warty.