bmw 645ci

Talk to Howie !

What's the key? Is it a regular of slot type?

If I'm not mistaken the 2006-up vehicles have the new body styles and Fortin may make a bypass module for it.  If I were you I would look more in detail to a wiring diagram from www.eautorepair.net Purchase the diagram for 10 bucks a  week and it will give you info on what you are getting involved in. That website belongs to mitchell and is for a do it yourself'er.  The actual mitchell program is used by Directed Electronics and is about 250 a month. I've used it and it has saved me a bunch

That is for 2006 and up not 2005.  You may be able to use a 556u.

I believe Enice is right, I've been having problems recently with Parrot kits on late (08) models, it appears adaptor leads before '05 won't work on Post '05. If you drop the lower dash around steering colum and the ignition leads vanish into a box around 6" x 4" x 2" you will need a Fortin CAN adaptor including by-pass kit. If you have a lead with the following colours you will be OK RED / Green, RED / Blue, Light Green, BLACK/ Blue (or Blue/Black) and Purple, you are OK and use a 556U but only  with the grey Valet key. My latest hands on research, i e find out when you're working on it tells me that there was a major electrical systems change about 05/6 on BMW's.