Over the seven model years, Porsche made a number of changes to the 914. Some of these changes were cosmetic and others were in response to changing crash protection standards. From 1970 to 1974, the 914 was offered with chrome or painted bumpers. In early 1970, rear bumpers were produced with a straight crease on either side of the license plate indent. Between 1970 and 1972, both front and rear bumpers were smooth without bumper guards. In 1973, bumper guards were added to the front of the car. In 1974, guards were also added to the rear bumper. In 1975 and 1976, the chrome or painted bumpers were replaced with heavy, rubber-covered units which actually made the cars more stable at high speeds.