Had this same problem. Dealer fixed it under warranty - said it was a dry bush / rubber ring that needed lubricant. They knew what it was straight away after I described the problem so must be fairly common issue.

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2009 e70 X5 30d MY10
Innovations | MSport | Carbon Black | Black Nevada | Aluminium Trim | 20" 227M | Panoramic Roof | Rear Side Sunblinds | 6NF | 3rd Row | Self-levelling Suspension | 35% Tint