I think a lot of them farm it out. My wife's jeep got taken to a local glass place when we dropped it at the dealer. We drove by that place to get lunch and were like hey that's your car!

How do you know which one the vehicle originally came with?

If mine is comfort IR coated as Qsilver7 pointed out.
You can see the coating cut out around the rain sensor (hard to see in photo) and the square in the center at the bottom (obvious in photo).

Decode your VIN. If your BMW came optioned with the comfort windshield...it will list option code S358A. If you have S345A listed for your windshield/windscreen...then you just have the regular windshield...or the regular windshield with RS (rain sensor) which is option code S521A.

If its not listed, but you do have it installed (based on the "cut-outs" that are obvious near the rear view mirror and base of the windshield)...then a PO has probably upgraded to the IR windshield during a replacement at some point.

If you haven't seen the links to decode your VIN that get posted monthly...here's your chance again to save both sites listed below...then enter the last 7 digits of your VIN , then answer the CAPTCHA question or puzzle correctly to indicate that you're not a "robot"... and get the info about your BMW (build date, interior/exterior color codes, standard & option list codes):

• Free Online BMW VIN Decoder, lookup, check - BMWVin.com
• bimmer.work : VIN Decoder for BMW

I recommend saving both sites because sometimes one may go down...this gives you another chance without having to wait for a site that's down to come back online. :D