They must have some excellent filtering
In addition to the new Glass Roof Mustang that goes on sale next summer
If not...I think they'd be wiser to release this in the fall/winter time frame, then people will see how nicely it warms there car in the winter as opposed to "it turns your car into a convection oven in the summer"
If they were particularly clever, they could have thermal active tint, that would become darker in the summer and lighter in the winter allowing the car to not heat as much and warm more respectively.