I'm pretty sure the 316 and 318 are actually 2.0
The 320 is actually a 2.2

323 and 325 are both 2.5 but in different tunes.

328 is a 2.8 and 330 is a 3.0.

All of the 6 cylinders ( 320 and above ) are shit on fuel all as bad as each other.

A 318 ci m sport goes ok. Other wise try and get a 328 or 330