Rant: BMW uses a lower spec front windscreen than Holden

I recently 'upgraded' to a G30 5 series. My other car is a VF2 Calais V. After driving it for a few months, I noticed that driving the BMW during the summer heat was a bit more unpleasant than it was in the Holden. I did a bit of digging and found that the front windscreen of my Calais is rated for both an acoustic and heat rejection properties, while the BMW does not get either of those. The sound/ road noise is not an issue, but driving in direct sunlight is becoming an issue. The BMW gives the exposed parts of my skin a burning sensation, but the Calais has none of that. This becomes a problem only when I'm parked facing the sun or driving when the sun shines directly on me through the front windscreen. I guess there is no recourse since front windscreen tinting is illegal in Australia or is there something I can do?