Tape alone is popular for attaching spoilers because it's easier and cheaper. But, it also has more potential for failure than the more secure method used by many body shops and also contemplated by BMW with this product - a tube of urethane, similar to what is used to retain windshield glass. It should be installed and "blue taped" for 24 hours with no body motion. I've only ever attached body parts like a spoiler with urethane. Imagine if a spoiler comes loose at highway speeds, about the level of the head of the guy behind you, and it's your liability.
https://www.ecstuning.com/b-genuine-...82699408866kt/
This post will likely be followed by comments that tape is fine and always worked for "them". Most of these same people will have homeowner's insurance even though their house has never burned down...yet.