So I managed to leave my wheel lock key on the lug and it flew off during a drive. Is there a place I can order a new key online, or do I have to go to a dealer for one?

 

Assuming you have genuine MB wheel locks, you'll have to take it to the dealer. They should have a master set and can match up the proper pattern key and order you a replacement.

 

I've lost mine before, what I did was find a socket that almost fit and then hammer it on, and then you can get it off.

 

And thats how thiefs get around the wheel locks.

 

Not knowing if I had factory or aftermarket locks on the car (third owner), I decided to dig around the side of the road further and with some luck I was able to find it in the ditch.

But for future reference, I'm assuming my locks and key are factory Mercedes, as the logo is on the back of the key in the attached pic.