Don't know about self-leveling suspension...think the adaptive drive is more electro-magnetic shocks that auto-adjust when cornering and where you can adjust the suspension stiffness via a button or iDrive...more of a performance feature than towing feature...know lots of people were complaining when they removed it from the sport package.....not sure what towing ratings are on X5, but I don't see where it would have a problem pulling 5k pounds...tons of torque...make sure to get a OE hitch and light assembly and maybe a load-leveling hitch assembly if it squats it down in rear....they are great and leveling out a tow vehicle

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2011 LCI X5 35d Space Gray/Tobacco Sport 20"
2009 E92 M3 Black/Black DCT 19"