Instead of having to take your eyes off the road, and refocus on instruments in different light conditions, a modern HUD simply projects information into your line of sight.

The difference can be invaluable. One American study revealed that if a driver's eyes wander off the road for more than two seconds then the chance of an incident doubles. Two seconds might not sound like much but, at 70mph, you'll have travelled over 200 feet - about the length of 14 cars. So, by enabling the driver to remain focused on the road, a HUD neatly helps counter this issue. Here’s how HUDs came about – and why you’ll probably have one on your car soon: