At first l thought it was the difference in the M35/45 regular and the m35/45 sport models but I've seen sport models without the spoiler....so if u know the option please answer, thanks

It is a add on

You order a spoiler.

You can get this one of two ways..by simply requesting the dealer to add just the spoiler which is approx $250 or so. Or the actual package option for this is the Aero Kit, which adds the rear spoiler, front/rear fascia (under the bumpers) and the side sills -- its basically a ground effects kit which runs you approx $1100. The M35 vs 45 or Sport model do not necessarily get you the spoiler or Aero kit by default.