Help... My Ass is Sagging...

[Crash513]

As you can see from the pictures, my ass is sagging, at least when parked. First picture is car after being parked overnight. Second is car after opening door and pressing start button, Third and Fourth are wheel views of the same. If anyone has experienced similar posterior slumpage, I'd appreciate your insights before I start spending a lot of cash troubleshooting this.

SAV: 2011 x5 35d, 85k miles

Relevant options:

• Adaptive Drive (Note: Includes Active roll stabilization active stabilizer bars, electronic damping control variable rate electromagnetic shock absorbers)

• 3rd Row Seat (Note: Includes 2-passenger, third row seating with independent climate control vents, second row manual fore-aft and backrest adjustments, 2 third row cupholders, and self-leveling rear suspension)

Symptom: Rear body of car sags after being parked for several hours. Upon entering car or pushing start, Ithe air pump runs and within about a minute, the rear suspension self levels the car. No errors on the iDrive, or service indicators.

I'm guessing this is probably a slow leak somewhere in the self leveling system. But I'm wondering what the most likely place is to start diagnosing this. Air bag? Pump? Sensor? Hoses?

Any experience or insights are much appreciated. TIA!