Originally Posted by +fireamx
John, did you look at the photos of the rear window of the concept car?
The spine in the rear window is simply a very slight "ridge" running down the center of the glass.
You can still see right thru it.
OK. A clear plastic stick on ridge, or... if you want to get more accurate, you'd need a glass shop to slump a piece of glass to the right shape, then glue it on with a nice UV adhesive.