The tax isn't really that bad, the difference is €25 per week, that's nothing really, it gets you into a car that just puts a smile on your face all the time. I would suggest keeping the 320 as well though, you appreciate an M a lot more when you can step away from it for a bit. I have a work vehicle and every time I climb into the M after driving it for a few days is like Nirvana.

You absolutely will not regret it and if you do, it's very easy to cash out, lose nothing and at least you can satisfy the itch. You won't regret it though, the reality of owning one isn't near as bad as the internet would lead you believe. Yes, everything consumable is nearly twice the price but you get used to it and it's worth every penny.