Ive been studying these for far too much time lately as getting one soon as i view a good one.

Ci means its a coupe with a injection (guessing), petrol engine

a Cd means its a coupe with a diesel engine.

330ci clubsports are a nice model. Come in the individual estoril blue or velvet blue, or silver. They have the spoiler, split rim wheels, front corner splitters and have 20 odd kg less sound deadening so u can hear engine more. They also sit a little bit lower than normal m sport models.

A true m sport will have sport stated on the log book. Alot of people put the bumpers and wheels on to make their lesser se models look like the more desirable msport, but alot dont bother changing to the msport steering wheel which has a little 'm' logo so thats one giveaway if its not a genuine one. M sports also have a 'm' badged gear knob and sill plates.

You can pick up low mile m sports coupes for about 5k for ay a 52 plate, with higher mile 04 plate facelift models even coming in at the 5.5k mark.

Be aware that they facelifted the e46 in 2003. Facelift one having different front lights, led rear lights and the newer style mv2 wheels, although imo the pre facelift still looks alright and u can get a late 03 plate pre facelift at a bargain price where most people want the facelift.

Im now starting to sound like a complete sad annorak so will stop now lol, hope that helped though.