I got my car back after a rash of problems including 'transmission slam', dynamic drive failure, etc. They reprogrammed the car (i dont' know which version) but its been working fine. Actually better than ever. The acceleration is noticebly better and shifts are smoother.

Big Draw Back: I noticed that my MPG took a big hit. My first tank after the reprogam was only 14 mpg!! I took careful notes and it was actually a little better. It went from combined driving of 22-23 MPG to 16-18 MPG. I used to get 350-360 miles per tank easily but now I get only 300-320. THis is a huge hit to the pocket book.
Would you take it in to the dealer or just enjoy the ride? I like the acceleration but at that' about $8-10 per tank.

Teriyaki

 

If I have it right MPG is calculcated over an extended period (last 1000 miles or something), yours likely reset when the software was updated. If it were me (and mine is in having 17.1 installed as we speak) I'd give it a few fill ups to see if things get back to normal - I doubt if this is anything more than your car losing the prior MPG history due to the update/

 

This is based on "actual" not BMW's software. I've been taking careful measures and hand calculating actual miles driven divided by how much it took to fill the car. Granted i may be off a bit but over last 8 fills, it should be close