I believe they are just non used buttons in the E70 and there just to be symmetrical. As mentioned, the E46 uses them for heated seats, but the E70 has no use for them. Unless it is options only available within the European market. But in the NA market, they appear not to be utilized.

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'01 740i Sport MKIV, Quad Brake Lights, Bi-Xenon retrofit, HID Fogs Dinan 7 Struts, Springs, camber plates, Intake, MAF, CAI, Throttle Body, NBT Retrofit, Strong Strut


'99 318ti Titanium Silver; '97 318ti Boston Green; '13 X5 3.5i Saphire Black Metallic
'84 633csi Black (sold); '88 325iC Black (sold); '97 740iL Black(sold); '01 740iS Black (sold);'97 318ti White (sold); '08 X5 4.8i Titanium Silver (sold); '96 318ti Alaska Blue (sold)