Protective cover for guide rail of a vehicle open roof construction

An open roof construction for a vehicle having an opening (2) in its fixed roof (1) comprises a stationary part with at least one guide rail (6), which is to be secured to the roof. An adjustable closure panel (4) is supported by a mechanism (5) which is capable of sliding movement in the guide rail. The closure panel (4) can be adjusted between a closed position, in which it closes the roof opening, and an open position, in which it at least partially releases the roof opening. The guide rail (6) is provided with an adjustable cover (111), which can be adjusted synchronously with the movements of the mechanism, or can be made deformable locally, for protecting the guide rail against penetrating dirt.