The spoiler on a street car is the undeniable victory of form over function.
This rack might work depending on how high the spoiler is. I had a '90 Eagle Talon with a wing back in the day and I just flipped the whole rack over so the curve was over the spoiler. Later I just broke down and got a proper Thule roof rack. Function won.
==
I contacted Bell Sports and complained about the lack of downloadable manuals. They said they are in the process of developing the website which will provide them.
http://www.bellbikestuff.com/
It has some basic stuff about helmets and tire changing right now. Stay tuned and check it once in a while.
In the meantime, they sent me the manual for the Doubleback/Tripleback Car Rack in English since that was the one I used as an example.
If you post your email to this solution I will be notified and will send it to you.