Get rid of it now!
I had the same issue with mine where it would sit half an inch lower sometimes. When I first bought it the shop kept it for a month for electrical issues. They replaced the ECM, gear shifter, some modules, battery etc... Then it was the blue tooth module and then front stabilizer bar. They replaced both rear inner lights twice and a regular rear light for a led that was out. Then I smelled fuel and replaced the vapor canister and it wasn't the problem. It needed a fuel pump and then the car started shutting down intermittently. That was a bad wire from the last fix. Picked it up and the fuel gauge stopped working. The aftermarket warranty was almost over in 6 months. When I took it in to get fixed I left it there forever and picked up a 2013 328 EB m sport.
Haven't looked back since. My wife misses the truck for hauling and size but I must have had 15k dollars of work done under warranty. My new motto is never own a BMW out of warranty!