I have been doing a little research if there is 2005 to 2006 BMW 3M with four doors and how much HP and fuel economy does it has and take. my result is only 2008 M3 has a 4 door model but I like the old model better and I'm thinking of buying one. so please tell me the detail and formation about the M3 4doors if there are any and what does I and IX in BMW stand for. thank you.