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A major objective of the European car manufacturers is to reduce the fuel consumption and CO2-emissions of passenger cars by 25% by the year 2008. As the fuel consumption is strongly related to the weight of the car, realisation of this objective will be achieved by long term weight reduction programmes. The European fuel tank market consists of around 14 Million units in cars, of which approximately 70% contain HDPE (High Density Poly Ethylene) fuel tanks, 17% leaded (Terne) steel, 3% aluminised steel and the remainder miscellaneous such as electro-coated Zn-Ni, galvannealed, hot-dipped tin or multi - layers with new substrates. The future legal regulations for fuel tanks will be dictated by the latest CARB (Californian Air Resources Board) specification LEV II (Low Emission Vehicle II). The main demand is the reduction of hydrocarbon (HC) emission for the total car from 2 down to 0.5 g / day in 2004. This demand appears doubtful for plastics, but is feasible for metal tanks.

During the last decade many materials were developed to improve corrosion resistance of automotive vehicles as to cosmetic and perforation corrosion. Tests were carried out based upon classic laboratory salt spray testing as well as on newly developed cyclic laboratory tests and on vehicle tests. To translate the laboratory test results into practice it is necessary to understand the corrosion mechanisms occuring in laboratory experiments compared to the corrosion mechanisms in real practice. This paper deals with the understanding of laboratory corrosion mechanisms in cyclic corrosion testing compared to some static outdoor corrosion tests. It is shown that delamination rate of scribed panels of painted hot dip galvanized, and galvannealed materials is highly controlled by the speed of anodic dissolution of the “zinc” due to the electrical characteristics of the corrosion products formed in the scribe and under the paint layer. These characteristics depend on the type of test.