For my 8/2011 X5, I purchased a USB drive from Tischer some months ago. It was on sale for like $89 or something. Took about an hour all told to update the system. Haven't used the Nav since then but even before, I never felt like it was providing the instruction too late.

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8/2011 X5 xDrive35d Sport, Black Sapphire Metallic, Black Nevada Leather, Fine Burr Walnut Trim
2/2001 M5, Jet Black, Exclusive Complete Black Walk Nappa Point Heritage Leather, Black Cubic Trim