Sometimes I'm just really happy being a Carrara user knowing Mark Bremmer is on our side. But seriously, I've read a bunch of explanations about angle this and angle that, but none as simple and easy as your example with the car window. Thank you, everything just made sense all of a sudden.

The only problem now is that I feel this urge to re-render anything I ever made with glass material since I always skipped the fresnel effect.