There is a 3.5L Duratec engine in the works that is slated for the Five Hundred/Montego/Freestyle, but I've heard that Ford is first going to make it an option when the Fusion debuts, and at the same time it will also become an optional in the Lincoln Zephyr and Mercury Milan. I've seen a lot of speculation on HP and torque numbers for this engine, usually in the range of 220-250.

I've also heard that, in light of the above, Ford might be putting off the 3.5L as an option in the Five Hundred/Montego/Freestyle until a these lines get a material "facelift", maybe sometime in '07 or '08.