Very little in it cost per mile as you have to work the 2.0i so hard. I'd say the 3.0i overall is far better in all ways including the issues mentioned. I'm not a hater but I think BMWs should have six pots, including the diesels.And over the years I've had loads of different variants. Main thing with the four pot is make sure services are kept up and things should be ok. Fingers crossed.
D