Might be a stupid question but I’ve tried looking everywhere on to what exactly this is. I’m trying to clean out the engine bay a little bit and sort out all the wire mess but I want to know what this piece is!

 

ABS modulator.

 

Out of curiosity, why is it missing on some cars?
My EDM MY2004 doesn't have it...

 

Are you talking about the cable going to the black box? Maybe, it's part of the smog pump setup, not present in later model F22s?

 

The black box next to the coolant reservoir with the cable is the cruise control box.....not on the 2006 and later with DBW. The black box next to the brake lines is the ABS modulator.

 

And not on nubbel's Euro '04 either! Cruise control was never standard outside North America as I recall (maybe not even available??).