I switched from a E90 328xi to F30 328i last last month and I find that while idling the sound feel so less of a luxury car. I also noticed the same when taking delivery but shrugged it off thinking it is just new car sound.
I metered 1600miles so far and the sound is still the same.
I don't know if it's my car or just that it is common with everyone.
Should I go to the dealer and have it checked?