Clunk on cold start
 

Every time I start Serenity I feel and hear a clunk from the engine bay as soon as i turn the key, the clunk does not happen if the engine is warm when I start it. I was thinking maybe starter? Is this a sign my starter's gear is going bad? Could it be something else entirely? My motor mounts are new.

Are the motor mount bolts torqued to spec?

Do you feel the clunk in the floor?

For the most part the clunk is felt in the floor. I have absolutely no idea what the mm bolts are supposed to be torqued to, so no.

Just snug them down and you'll be fine.

Try this after the car has sat for a long time, open the hood and stand on the passenger side of the facing the motor grab the motor with both hands and pull, listen for a sound that is like what your hearing. I had the exact same issue on my 280CE. Turned out to be a cross threaded motor mount bolt, I didn't replace them, a mechanic did many years ago.