It doesn't.
The reflectors in car's headlights' are concave.
The Rear view mirrors are convex The Headlights are concave
The wing mirror or side mirror of a car is convex. It curves out to be able to see with a wider angle.
in a car
Concave mirrors are used in headlights.
concave
car
No, that is not allowed in the US
Convex mirror make small images and hence provide a wide view of what is happening behind your vehicle. Therefore, they are used as driving mirror.
It dips the mirror so that headlights from the car following don't dazzle you.
Concave mirrors are used to focus light, to produce a parallel beam in car headlights, and so you can have a close look while shaving. Convex mirrors are used for making telescopes, viewfinders in vehicles, and used in supermarkets or stores as surveillance as it gives a wider view.
A convex mirror will always create a virtual image. It will also have a negative magnification. The passenger side mirror in every car is slightly convex. [The one with "Objects in Mirror are closer than they appear"] Also, anti-theft mirrors in convenience stores have these properties.
convex: to help the driver see areas behind and to the sides of the vehicle,which is in his/her blind spot.