I'm considering getting rid of my E90 M3 as its causing some friction at home, I can't be arsed with tyre kickers/dreamers so I'm considering selling it to a dealer,

Now what's involved? Ringing up sales managers and asking if they would be interested in the car and taking it from there?

I've bought plenty cars, but never sold one back to a dealer

- As soon as you ask a dealer to purchase outright they will bite hard as they assume you are desperate. Plus E90 M3's aren't great sellers. Factor in the imminent release of the M4 and everyone wanting to cut their e90 M3 loose then they will offer well below book to allow for it sitting on the forecourt for a while.

ps - why is this a wiki?

I have no idea I never meant for it to be, I will report it and see if it can be changed

I would be more than happy to buy your M3, I love e90 M3