A plastic window for use in a motor vehicle includes a plastic panel having portions defining an edge about a perimeter of the panel and a window flange integral to the plastic panel. The window flange is positioned adjacent to the edge and extends at least partially them along. The window flange includes an engagement feature configured to engage a corresponding engagement feature of a window frame. A window assembly Includes the plastic window and a window frame configured to be attached to a motor vehicle. The window frame has portions forming the corresponding engagement feature which receive the engagement feature of the window flange to secure the plastic window to the window frame. A method of installing a window on a motor vehicle is also disclosed.