Sounds about in the ballpark. Depreciation is heaviest in the first couple years. A new model may cause a small hit. The end of the warranty on these cars is another hit. Then it levels out for a long time, assuming the car is well-maintained. Looking at my own car at Edmunds, I have lost ~$11K since July of '11. You must have more miles on yours, or wagons hold thier value better than coupes. On the other hand, IMHO I have certainly gotten $11K of use and enjoyment out of the car.
That said, while the numbers are bigger (scary big, really), on a percentage basis these cars hold thier value quite well over time. Other expensive cars are often much worse, and more expensive cars are MUCH worse - if you want to have a heart attack, check out the depreciation on a loaded 7-series the first few years. You might as well burn $20 bills while driving.
I plan to keep my '11 wagon so long that the depreciation is but a distant memory.
'11 328! Touring - Tasman on Chestnut, 6spd manual, factory upside-down "i" option
'16 M235i - Estoril on Oyster, 6spd manual, sunroof delete