As long as the crank speed is consistent to normal temp crank speed then you should be fine. Everything is very very cold around 0 degrees for an engine and starting is is a challenge. It's normal to have weird noises at that temperature.
My e30 does not like to start in the cold. It'll start but it sure doesnt like it. Haha. My e46 is much better. It might be a little loud at first in cold temps but all is well. Totally normal.