This ML has been through four winters, two PS clamp replacements at the dealer, and a PS flush at the dealer already. This startup noise has happened every year at roughly 10F.

I'll try the rotate steering wheel thing, but doubt it'll act the same way as yours. After the engine warms up (I let it sit for about a minute until the engine revs drop), the steering makes no noise. Of course, we're in a virtual heat wave (34F today) now, so I won't be able to reproduce this until the next cold wave or probably next year.

It just sounds a little weird on startup before the engine grabs. It's almost the engine fires up and spins the starter motor for a while at a higher speed than the starter motor wants to go (the high-speed whirrr noise that's precedes the vroom in that video I posted).