The seven main reasons why we do this.
1. If the car in front were to roll backwards, we would have a buffer zone.
2. Should we slip off the clutch whilst in gear, we would have a buffer zone.
3. Should the vehicle behind us misjudge their stopping speed and hit us, we would have a buffer zone to stop us hitting the car in front.
4. Should the vehicle in front of us break down, we would have a buffer zone to be able to move out around that vehicle.
5. The exhaust emissions coming from cars are dangerous, and contain many chemicals. One of those is Carbon Monoxide, this can be fatal. Sitting too close to the vehicle in front, especially when your heating or Air conditioning is on, you will be filling your car with those fumes!
6. Giving space to pull to the left in the event of an emergency vehicle coming up from behind.
7. If the vehicle in front was a large vehicle without a rear window, they wouldn’t see you if you were too close. You need to be able to see their mirrors for them to be able to see you. In addition it would give you a better view of the road ahead.