When I was at the MB stand the other night, I asked one of the reps. about the upcoming CDI's and your question when we're gonna get an ML550/R550.
She said the CDI's won't be selling in all 50 states. So, no ML320 CDI, R320 CDI, E320 CDI and definitely no S320 CDI in New York. I think only that Bluetech engine in the E-Class will meet all 50 state emission requirements.
The ML550/R550 (and the CLK550) will be available sometime during the summer.