I'm suffering the exact same problem after an accidental overfill in my SLK 230. Gas fumes are terrible! Where the heck is the vapor recovery canister on my car?

 

My 2001 SLK does the same thing. I can fill to about 3/4 full, then if I want to put in more, I have to keep clicking a little bit at a time. Takes a long time to make it full. I thought all SLK's were that way. I've tried all the tricks, nothing makesany difference.