By Joshua T. Johnson, P.E.

U.S. consumers, businesses, and government organizations own over 200 million registered vehicles. Assuming an average value of $5,000, the total investment Americans have made in vehicles can be estimated at more than $1 trillion. Until the late 1950s, corrosion of motor vehicles was limited to marine environments; however, with the increased use of de-icing salts, vehicles in the snowbelt regions began to corrode and literally fell apart within a few years after purchase. In fact, in the 1970s the cost incurred by corrosion was so high that in the Battelle-NBS study, the automotive industry sector was singled out as being the main driving force of corrosion costs to the U.S. economy.

In the late 1970s, automobile manufacturers started to increase the corrosion resistance of vehicles by using corrosion resistant materials, employing better manufacturing processes, and by designing more corrosion resistant vehicles through corrosion engineering knowledge. Because of the steps taken by the manufacturers, today’s automobiles have very little visible corrosion and most vehicles survive structurally until the vehicle wears out mechanically. The total annual cost incurred however, is high and much can be done to further reduce the cost.

The total cost of corrosion to owners of motor vehicles is estimated at $23.4 billion per year or 79 percent of the transportation category. This cost is divided into the following three components:
(1) increased manufacturing costs due to corrosion engineering and the use of corrosion-resistant materials ($2.56 billion per year), (2) repairs and maintenance necessitated by corrosion ($6.45 billion per year), and (3) corrosion-related depreciation of the vehicles ($14.46 billion per year).

Twenty-five years ago, corrosion was of obvious concern to the general public because of visible rusting of car bodies and frames. Because there is generally no extensive car body corrosion being observed in less than 10 years, it is commonly believed that corrosion is not a consumer problem anymore. While there exist few opportunities to further improve corrosion resistance of the body of motor vehicles, some areas for improvement in individual systems must be mentioned. These include fuel and brake systems, as well as electrical and electronic systems. Many failures of the latter component are due to corrosion, but because damage is not visible, there is very little public outcry and components are merely replaced. Manufacturers are however slowly upgrading and protecting electrical and electronic components from the environment to ensure a longer lifetime.

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