If you’ve been driving roads that are frequented by 4x4 drivers, chances are you’ve noticed these strips of reflective material on the bottom of the windscreen. But what are they, and do they offer advantages?
What are Dash Shades?
Dash Shades are strips of insulative material that cover the bottom 150mm of the windscreen. They are locally produced by Solar Screen in Capalaba, Brisbane, alongside a range of other shapes and configurations. Originally, Solar Screen produced insulation that covered the entirety of the vehicle’s windows, giving a blackout effect.
Some truck drivers, caravanners, and tourers would tint the bottom of their windscreen to reduce glare reflecting from the road and bonnet, which reflects inside the cabin of the vehicle. Combined with visors and sunglasses, these drivers could significantly reduce eye strain and the amount of UV entering the cab. This tint is especially helpful when the sun is low, as sunlight reflects off the bonnet and directly onto the eyes. With this in mind, Solar Screen’s creators used their existing material to create a strip of fabric that could be easily added and removed to the windscreen. Below is a visualisation of the benefit of solarscreen when travelling into a low sun - it's a lot easier to manage when paired with sunglasses.
Opinion:
After having used a dash strip on my Toyota Landcruiser 80 series, I can confirm that these strips do make a difference on long drives to the temperature within the cab, the light in the cab, and 3) the reflection off the bonnet. Although we'll need to do further measurements to prove whether there are noticeable ambient temperature decreases when using a dash screen, a thermal camera proves a signicant amount of UV radiation is transferred to heat when driving long haul routes, which would have an impact on the temperature within the cab. See below for the image: 
The dashboard is significantly hotter compared to other surfaces within the car. Like other owners, we can confirm that these dash screens do make a large difference to the comfort of the vehicle on long drives.