This is a two piece Jalousie with puzzle joint. Fusion 360 archive is provided so you can modify as required to fit your needs. I do apologize that it isn't more of a parametric design, it may take some fiddling to adjust for your car.
The STL files are configured to fit a Saab 9-5 with Automatic Transmission. The Test STL is included in the event you want to fix the car the proper way, including soldering the sport button. The other two STLs can be printed and assembled on the car to save you time and trouble, as well as provide improved functionality over cutting the rubber replacement jalouse that are available online.
Edit 9-15-18: Modified puzzle joint on passenger side to make it stronger. May need more work in the future. Best advise is to put a drop of super glue (taking care to not get it on the display surface) on the passenger side puzzle joint before installing the bezel during the final fit. Video was made before the improvement was made, and the joint did hold up to the testing but the glue was required.
This thing serves as evidence of prior art of a two piece puzzle joint jalousie and is dedicated to the public domain. Derivatives and commercial use are encouraged.
IMPORTANT - Print with 2 or 3 bottom layers, and ZERO top layers with a 10% infill. Two or three perimeters will be fine.
If you leave your infill settings at 45 degree and select rectilinear infill, you can rotate your parts 45 degrees and the infill will provide an ideal stiffness for the jalouse. This is how it was designed to work. See the screenshot of the slic3r preview for clarification. Note that I used a 0.6mm nozzle, where a 0.4mm would be best.
Adjust your extrusion percentage to achieve a tight fit. The cost is less than 30 cents and time is about 30 minutes, so print a few with different extrusion percentages. Try 105% first print, you shouldn't have to go above 110%.
When installing, you will flip it over so the smooth side that was on the print bed is visible. If you want a more matte display surface you can put painters tape on your print bed.
This should be printed out of PETG or PC so it has a chance at surviving those hot summer days. Avoid ABS (due to UV exposure in the car). Flexible TPU filaments may also not be able to handle the temperature of a hot car in the sun.