Having only had my X6 40d for a year and a half since new, I will be retaining all the factory fitted badging on my 50d as it has cost me about £4k a letter in depreciation!
Also, it's a diesel M car - not only through its livery ('sports trimmed' models also get the livery) but through the addition of a comprehensive power (the most powerful BMW diesel engine ever) and handling set up, unique to the model and taken from the petrol M cars, which is activated via a sports switch. That's pretty close in my book.