According to the hunter alignment machine you are supposed to set ride height w/ full tank of gas and 450lbs in the passenger compartment + 50lbs in the trunk.

I would assume it's trying to help you from having your 20's rub on the fender well's while running from the cops...

I'm no expert tho

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2006 X5 48is Black / Black - LED AEs - FCAB - GAS 1.2bar cap