This may be bad news...
BMI's Mile Checker online - https://www.flybmi.com/bmi/en-gb/fre...williearn.aspx (must be logged in to view) shows the following MAN-ORD:


Calculation results:

You’ll earn the following number of destinations miles:

business class = 7630
upgraded economy = 5722
full economy = 3815
other economy = 1907
web only = 953

The W Fare Class would be a "other economy" fare, so only half miles:


miles earned on bmi
fare type no of miles earned applicable classes
business fares x 2.0 c,d,j
full economy fares + the new economy (transatlantic) fares x 1.5 y,s,u,l
economy fares x 1.0 b,k,m
discounted economy fares x 0.5 h,e,q,o,v,w
web only fares x 0.25 t

(Interestingly, their own mileage calculator conflicts with the fare-buckets: "Full Economy - Y" should earn 1.5 miles according to the T's & C's, but only 1.0x according to their little utility...!)