AbstractA range of commercially available automatic transmission fluids (ATFs) was tested, in order to compare their performance both with each other and with broadly accepted European market requirements. The test results showed a considerable variance in the performance of the fluids, despite their conformity to a common ATF specification. Furthermore, when the latest transmission developments are considered, it becomes clear there is, in many instances, a divergence of performance requirements. One area of potential conflict is the different emphasis on passenger cars as against commercial vehicles in the North American and European markets. The paper examines factors that influence ATF performance requirements, and the areas of compromise if a common fluid is needed. Suggestions are made to address those circumstances where it seems that performance needs are too divergent.