Standard equipment on the upper trim levels is: "Leather-trimmed seats with seatback pockets; 8-way power-adjustable driver's seat with power lumbar support; 8-way power-adjustable front passenger seat". You can actually get Cloth and Softex on lower trims.
"Leather trimmed" is a key word, I think. If it's anything like my Mazda, only the center panels of the seats that touch your back and ass/upper thighs are leather, and every other piece is "leatherette". If I remember right, in some BMW 3s series (and it may even be the case in my car, I don't know) only the front seats had leather, the back were all faux leather/polyurethane, aka PU (which isn't used that much because when you say it, it sounds like "pee-eww").
UltraFabrics has a line of polyurethane faux leathers that I've used in a commercial upholstery setting, and it holds up damn well, even compared to real leather, which actually stretches more than some faux leathers. They colors age quite differently, but as far ad durability does, I've got nothing against high-quality fauxs....
but disclose it, damnit.