Save yourself the hassle and sell it to one of the car buying sites. You'll have to manage your price expectations a bit, but it's quick and easy.
I sold my M4 last month using
www.wizzle.co.uk and got an asking price offer the same day, paid for and collected the day after.
Job done
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2019 BMW M5 (my daily driver)
2002 Mark's D2 S8 FE
2020 BMW M340d xDrive (Anely's daily driver)
2000 FL D2 4.2 QS - SOLD 2011