It's no secret that I am sun-averse. Not because I don't like the sun, but I've had a lifetime of UV exposure already and then some and would keep to a strictly vampire-approved schedule if my dermatologist had his way. I'd try the self-tanner route if I wasn't afraid to end up carrot-orange, but as it is, I give off a radioactive-white glow that can be seen for miles.
At any rate, as the crazy mother of three kids who have a lot of activities between them, I spend a lot of time driving. My car is permanently equipped with my sunhat, sun wrap and a bottle of sunblock so that I am always prepared for the hours on end of soccer games etc, but it occurred to me recently to wonder how much sun exposure I was getting while in the car en route to all these places. I called the dealer, who didn't know for sure. Just for giggles, I looked online to see if there was anywhere to submit the question, and found the Volvo Customer Care website (I drive an XC90.) I'm sure other manufacturers have a similar site.
A very helpful representative responded to my question almost immediately. Apparently UVB rays don't go through glass at all (who knew?) and most UVA rays are blocked by the treated glass from which windows and windshields are made. In my car, more than 99% of UVA rays are blocked by the windshield and about 82% by the side windows. Happy news for your friend Dracula here!