You cannot use wax on glass, i'd go with something like AG Glass Cleaner.
theres always the exception to the hard and fast rule. i have used a wax spray polish on my cars for years that coats bodywork, glass inc windscreen and acts like rain x but lasts longer. it stops the dreaded bugs squash sticking and when used inside the glass kids dont leave fingerprints on the surface or dogs muzzle marks ,my pet hate if you will pardon the pun
you can use it on painted brake calipers to stop brake dust becoming a pain to remove and alloy wheels stay cleaner longer, then just a wipe with cold water and sponge or hp hose
my son sells this product to lorry companies tractor/jcb drivers, trawler owners, also light aircraft owners to polish the planes and many other people buy it for home use also shower cabinets ,tiles windows etc its a teflon spray that is easily applied and wiped on to surface then cleaned off with a micro fiber cloth ,full car in 20 mins
it does not mark plastics and leave white streaks. he als has another coating that cleans grainy plastic and removes polish marks leaving a teflon coat /non stick satin finish
here are some of our old cars polished with the teflon
this pic below shows bodywork, glass, wheel and sill coating shine
nearly ready to get the new slk done
if anybody is interested in the polish or wants info get in touch he sells the 330ml can for £15 each but has done bulk buys for discount
as you can see i love my cars to be clean, even my track car,this is a picc after an event ,quick wash and into garage
sorry about the double slk pic cheers geo p