Glass is one of the easiest materials to recycle, so you won’t be surprised to read that your car windscreen and windows are recycled. But the way in which they are recycled poses a few problems.
Most of the times, It is removed from the car before the car is crushed. The glass panels are then sent to a glass recycling centre, where they are processed. This usually involves removing the plastic laminate from the glass (which is a legal safety requirement) and breaking and sorting the glass according to size, purity and colour. This glass cullet (small pieces of glass) can then be used to create other glass products (flat glass for windows etc., glass for containers, fiberglass, and aggregate for construction materials.
If your car is crushed with the glass still in place, the glass then has to be sorted from the crushed materials and processed into cullet. As the glass is broken and crushed, it would take a lot more processing to process it into high-quality cullet, and so this is not commercially viable. Instead, the glass usually goes through a less intensive sequence of sorting and processing and is used to create lower quality cullet. This cullet has much fewer uses, for example, it may be used as a secondary aggregate in the construction industry but would be unsuitable for use in glass containers.
From a recycling perspective, the preferred method is to remove the glass panels whole, as this makes it easier and more cost-effective to recycle the glass into a higher quality of glass cullet (pieces of glass). The technology exists to remove the laminate safety sheet from the glass quite easily, and so this leaves a greater percentage of uncontaminated glass.