To summarize the experiments, adding a single Ge atom reduces carbon deposition by a factor of ~three, but there is still significant carbon deposition for Pt4Ge, amounting to two or three C atoms/cluster after 6 TPD runs. Nonetheless, the Pt4Ge clusters retain most of their strong/high temperature ethylene binding sites, even after 21 TPD runs, while these the high temperature sites are almost entirely suppressed for Pt4/alumina. Questions we seek to address are: Why is carbon deposition only partly suppressed for Pt4Ge/alumina? What is the nature of the strong (high temperature) ethylene binding sites retained for Pt4Ge but lost for Pt4/alumina? And why, despite retaining strong C2D4 binding sites, does Pt4Ge clusters nearly stop producing D2? DFT was used to address these questions and also to examine the activity of the model catalysts for the ethane-to-ethylene dehydrogenation reaction, which cannot be studied under surface science conditions.