Replace your blue coolant cap with this new design found on Tiguan MQB and MK7.5 models. It's smooth top and and grips around the outer edge make it a visual and functional upgrade if your car came with an unsightly blue cap or even the older style slotted black cap.
The washer fluid cap is not just for looks either. It keeps dirt and debris from entering the washer fluid pump and lines and clogging them up, and keeps the washer fluid from escaping and being wasted. Due to the temperatures reached in the engine bay, the cap can sometimes become brittle and crack, or even just fall off.