The use of cathodic protection for metals can be accomplished by sacrificial protection and impressed current protection. This paper discusses the application and misapplication of cathodic protection to automobiles. Fundamental principles and requirements for successful use of this technology are reviewed, including the important effect of electrolyte resistance on current flow. Laboratory and field tests show that in the atmospheric automobile environment, cathodic protection beyond a few centimeters from the anode is not possible. Distributing the anode, such as in galvanized steel, solves the problem for sacrificial protection and therefore, this technique is used extensively on automobiles. However, distributing the anode for impressed current protection of automobiles is not currently economical. Therefore, successful commercial application of impressed current protection of automobiles has not occurred.