Count me as skeptical re: Glass passing UV light. Why? Because I don't believe you can get a tan indoors, through a glass window. I don't even think you can tan through plain old plate glass either. It would be easy enough to do a simple test outdoors with the Sun overhead.
Regarding the heat you feel on your left side, while driving with the windows up. That's predominately infra-red. Glass is very transparent to that. If not, glass baking dishes wouldn't be used in ovens. The only "light" inside of a dark electric oven is from IR radiation. There is no UV source. Therefore, you can get burns and blisters from IR sources. And glass can become screaming hot enough to lose your fingerprints on. It is a high emitter too.
All glass in a modern auto is going to be laminated as well. Not just the windshield, the side windows and back. Penetration is not only determined by the Sun's azimuth, but by the angle of incidence as well. Some windows & windshields are far more sloped than others.
Soon after I bought the sled, I had 3M metal-film tint installed, as the car is like a terrarium with all the glass. I recall they had to remove the metal film in the rear due to it intereferring with radio reception. So a non-metal 3M dyed film was installed.
Finally, I sprayed in a radiant barrier paint to the bottom of my roof decking several decades ago now and it made quite a difference to my attic temp. Now, even during the Summer when the Sun's on the meridian, the dT between outdoor shade air temp and my attic is less than 12°F. I know because I have a temp sensor installed there long ago when I was actively experimenting with passive cooling techniques. The paint contains fine aluminum particles, a low emitter, that lowers the radiation from the hot roof deck, into the ventilated attic space. Very similar to the fine metal particles found in 3M's window film. They too use a low emitter.
Interesting topic you've raised OP! I'll need to read up more and do my tan-through-plate-glass experiment one day outdoors.
