[ddbach]

I'm about 90 min north of Chicago and agree w/ gprsh924 on rwd vs awd. If you are in an open more rural area awd may have some benefit a few times a year but I have not found that to be the case in the western burbs of Milwaukee.
N54 engine is fun to drive. I like it better than the na 328i I drove as a loaner for a couple of days when my fuel pump was replaced though part of that may have been AT(loaner) vs MT(mine). The fuel pump issue seems to be occurring less often to fewer people with the latest version of the pump. It is covered under a separate warranty for 10yr or 120k miles so with your plan to drive for 2-3yrs you would be covered. If you are buying CPO it very likely has had the pump replaced under a recall already.
Sport pkg in an xi mainly gets you sport seats no sport suspension. Also looks like if you would want MT that is not available for 535xi but is for 535i.
Fuelly.com is another place to look for gas mileage. Posters there look to be doing slightly better than gov figures. Of course traffic around Chicago may place you towards the lower end.