I agree if money not a factor then the M. However I would go with comfort seats as the sports seats are a big let down - just a standard sports seat and for me was really uncomfortable after just 20 mins.

Also be prepared for a turbo 4 cylinder sound. The 50i strangely sounds much better than the M.

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2009 135i M Sport Convertible
2008 X5 3.0si
2003 E46 318Ti M Sport Compact - donated to parents
2003 116i Hatchback - donated to brother
2002 316Ti - Sold
2000 318ci M Sport - Sold
1998 318i Sedan - Sold