I hit something on the road last night and I think it is the cause of my undercarriage getting cracked. I'm not entirely sure if this is the cause. Every time I reverse, I hear a rattling noise. To me it sounds like some pebbles went up the crack and are rattling inside the undercarriage. It only makes the noise when I am reversing, not going forward. it is on the passenger's side right under the passenger door.

how much does it typically cost to fix/replace an undercarriage?

 

I don't think that is your undercarriage man. It appears to only be plastic underbody panels. You may be able to just remove it and leave it as is. I personally would replace it.

No idea what Mercedes wants for those.

 

yeah it's definitely plastic, and it's only on the passenger side, all other sides are fine. I won't be doing it thru Mercedes anyway, will take it to my guy and see what he can do about it. I wouldn't have even noticed it if it wasn't for the rattling noise, that's what made me check underneath and I saw the crack. Hopefully this isn't a big deal.

 

Looks like substructure cover (70 in diagram) shop part # 2076800208 used, 2076806200 used/new; plastic nut 0009903162 (90, there are 7 total) if needed see attachment.