This is kind of related to http://feedback.arma3.com/view.php?id=11810, but I felt like I needed to dedicate a ticket to it.

Functioning windscreen wipers for cars and helicopters.
Basically it would just increase the atmosphere when it's raining and you're in a car...or even helicopter. Starting the wipers would either be in the action menu, or just happen automatically as soon as it starts raining.

If you have RHS: Escalation, some of the vehicles such as the UAZ has this feature. Wouldn't you say it is much cooler to drive in the rain with that?