A protective cover for a vehicle comprising a sheet or a web of a flexible material that possesses a property of buckling or curving in the upward direction from the vehicle with the formation of a canopy-type shield for protecting the vehicle from direct sun rays, birds' droppings, etc. The sheet has a length exceeding the length of the upper surface periphery of the vehicle so that the upwardly curved canopy is formed either by applying two oppositely directed forces to the opposite ends of the sheet or by prestressing the sheet. The sheet can be made from plastic or a fabric that incorporates springing metal strips that tend to curve upward when they are in a free state. The sheet can be conveniently stored in wound state in a cylindrical cassette. Storage of the flexible material in a wound state enhances the property of bucking or curving when the sheet is withdrawn from the cassette.