One of the more effective ways of improving automobile fuel efficiency is by reducing vehicle weight. This can be accomplished through the use of higher strength, lighter gauge steels. This study concentrates on two such steels (renitrogenized and dual phase) that potentially could be used in some fatigue applications.Three dual phase steels with different monotonic strengths were tested, as was some dual phase which was exposed to undervehicle corrosion. Two renitrogenized steels were also tested, as well as a mild steel of similar carbon content. These were tested in the hot rolled condition, and also after forming and aging. Some samples were also cycled intermittently to simulate stop-and-go driving. The data was compared to previously determined HSLA data.