The electric motor noise sounds like a small turbo spooling...It was much louder on the Mini...I actually prefer it to a loud S54...
Trunk space is a set of golf clubs and maybe 3-4 grocery bags. It's in a L shaped configuration so it's not like you can put a large box back there. Funny thing is that under the hood, there's about 1 ft by 1ft by 3 ft of empty space. I'm not exactly sure why that's there.