The Pulse and the Passion are basically the same car. The Pulse, not sold in the US, is a little more performance oriented, with larger tires and wheels, and some minor suspension upgrades. It is still below the Brabus, but a little more costly than a Passion. If I remember correctly, the Pulse offered the same engines as the Passion/Pure models. The grille should be a direct replacement. Good luck, George.
I went on a multi-year hunt to turn my Passion into a Pulse with the help of DOZENS of people from this and many other Smart forums, including a super kind gentleman in Mexico that was the recipient of Upstate NY half moons due to his help (and translations) talking to a Mercedes dealer he knew very well south of the border for us.
The front and rear panels, after my search (I hope I wasn't the cause of this) were blacklisted or whatever you want to call it. As in event with the part number, Mercedes can't / won't order them anymore. At least, that's what two northeastern dealers told me. I was already to buy doubles or triples of the valances should anything ever go horribly wrong.
There was one other gentleman in Florida that did the same thing to his car, and unfortunately that vehicle was totaled and gone (including the Pulse panels) before I knew. He had a site set up chronicling his journey, too.
All the panels for all the 451s are interchangeable - Pure, Passion and Pulse. The updated lower grille (1-piece) requires the updated lower valance and clips to go below it. The grille for the Pulse overseas, to my knowledge, is the same grille for our cars. We got black and silver here just as they did on the Pulse.
It is correct that the Pulse was a spec bump overseas. I'm not sure if it included the MHD with start/stop, but it also came with a suspension upgrade and larger tires on the standard rims. The tire size & wheel width update eventually made their way over here. The MHD and tuned suspension did not.
Anywho, as ALL OF MY POSTS turn out to be, apologies for the thesis paper on what started out as a grille question. In all my hunting to turn my car in to a Pulse (largely successfully down to the badges) I hadn't came across a newer grille. I outlined the difference in that thread in the first sentence here - now where did that go? Ah, WAYYY up there.