Rate my combustion :-)

[Rombbb]

Z4M, new plugs, have only been in for some 50 miles but somehow on all of them one side is pretty white and the other pretty black.

Is that normal ?

Checked valve clearances and only 2 were out of margin, being 0.24mm.

Car seems to drive fine.

[cyruscat]

Yes, it looks normal.
Why do I say that?

Think of the plug sides oriented toward the intake valve where they get hit with incoming air and fuel. They stay clean and white.

And on other side they face the exhaust with burnt fuel and air going out. They get dark.

Depending on fuel brand or additives I have seen different colors on the intake side.

Overall look at the dark side and hope for light to dark brown color.
Black and even crusty says poor combustion or oil contamination.

For fun reading and good info do a web search for reading spark plugs. Some people made an art of it