I have a Peruvian friend who refers to car windows as "las lunas." "Bajemos las lunas para que se enfríe el interior del auto." I don't know if it's widely used in Peru, but I just thought I'd pass it on.
Hi gunslingingbird. Thanks for your interest in our dictionaries. Though ventanilla seems to be more common for this, luna is perfectly valid (see the Wikipedia articles about lunas de automóvil and elevalunas.) I've added luna to the translations proposed under this entry. This addition will be visible once our databases are updated in the next months.