15.5 T5 FWD -- brand new, awful MPG
 

does it take time for the computer and engine to evolve? If so, how long?
Just took delivery last week. 250 miles. getting 15MPG avg.

Try using the eco mode if its the drive E engines

Are you talking about the first 250 miles on the car? If so: yes, you should not worry about horrible mileage. I wouldn't even look at it until you have 1000 miles on the car, and wouldn't worry about it being low until you have 2000 on it.

K, I'll give some time. Turned on ECO+. Is there a way to make ECO+ default, as there is S/S?

Also if you leave it in "sport mode" you will use more gas!

If there is a way to force it to stay in ECO, I haven't found it. I just made two 1100 mile trips fighting a nasty head wind both ways and got 31mpg the first trip and 34mpg the second trip.
Unless you're taking very short trips, I would expect your mileage to improve with time.

Scroll through your computer to find average MPH. When I was averaging 16 MPG, I was only averaging 14 MPH in mostly city driving.