>   Years ago, an intelligent person told me that non-tinted windows were
> better, because the UV rays that penetrated thru the glass could likewise
> exit almost as freely, but that a tinted window (which reflects most but
not
> all UV rays) ultimately traps more UV (and therefore more heat) inside,
> because the UV that enters the car has greater difficulty reflecting back
> out of the interior.

Please don't confuse Ulitraviolet radiation with Infrared radiation.  The
two appear at opposite ends of the visible light spectrum and consist of
differing wave lengths.  It is Infrared radiation that heats the interior
while the Ultraviolet (UV) damages the interior.  The question to ask would
be how well does dark tint reflect or absorb infrared radiation which I
would imagine could be easily tested with, what else, an infrared heater.

See here: http://csep10.phys.utk.edu/astr162/lect/light/spectrum.html

Chris S.
'85 Westy
www.knology.net/~vw/
http://groups.yahoo.com/group/wolfsburg_campers