Does anybody have any information on how difficult it would be to buy a used German M5 and ship it back to the US. Does anything have to be done to the car to make it US compliant?

 

I'm not sure about how things work now but back in the 80s, when there was a more favorable exchange rate between the US dollar and the German Mark, there was big business in federalizing "grey market" cars for import into the US.

There were various things that had to be changed to make the car US legal. For example, you had to change the side marker lights from clear to amber (and you had to use "sealed beam" headlamps back then), you had to add crossmembers inside the doors, etc. Nowadays, there may be crossmembers in the doors already so I don't know what else it might take to convert a car from Germany to the US...

 

Convert Kgs to stupid lbs , Kms to miles, etc, etc.