Maximum presser foot lift on these models tend to be around 5 millimeters. On some you can push it just a bit over seam bumps with out getting into trouble. I can fit numerous layers of the standard faux leather used for bike seats (it's reasonably water proof with out any upkeep). I think I sewed through two and three layers of just over 2 mm thick white cow hide without any trouble. Leather quality varies a lot, and you need the firm top quality for seats like that. On
Leatherworker.net there are a few guys who knows all about the new and vintage models ideal for thicker leather.