Cars have a warning on external rear view mirrors saying "Objects are closer than they appear in the mirror." Explain why the warning is there.

A car has a convex mirror because a convex mirror placed on the passenger side reduces the driver's blind spots on that side of the vehicle by presenting a wider field of view, but it also makes other cars appear farther away due to a slight distortion caused by the shape. The flatter mirror on the driver’s side produces a more accurate depiction of what’s behind the car but with a more narrow field of view. But while driving wider view is preferential so the mirror is curved.