Wow. Just a thought...but if you get a lot of sun & heat build up during the summer...this could be a good time to upgrade to the "climate comfort" windshield if you don't already have it.
This windshield helps with UV rays etc to help reduce heat build up in the interior. You can ask the installer to order the bmw part nbr the windshield that applies to the options you have...it's good to check the correct part nbr regardless if you want to upgrade the windshield or not:
RealOEM.com - Online BMW Parts Catalog