Well, the major thing that conspires against the HemiX is the location of build.
Had the car been built in the US, the factory would have had access to the Hemi that is currently produced in Mexico; to the tune of 400,000 units per year. Compare that to the MB 3.2 How many of those are produced anually? 75k? I don't know; but the number of cars that MB produces pales in comparison.

Cost would undoubtedly drop.
Technology is not just for technology' sake. I'd take a pushrod Hemi with Displacement on demand technology in it over the OHC stuff in the MB motor. KISS factor. And with DOD it'll probably get better mileage than the v6. At least on the highway.
Total weight added from motor alone would be about 200 lbs.
Why doesn't DC take a page from their own concept car and make some panels of Carbon fiber.

Good handling does not always stem from 50/50. The only major revisions to the suspension would be stiffer springs/swaybars and the accompanying shocks to go with them. Not that big of a deal.
It's a mute point. Chrysler won't do it, but it makes for good bench racing.

My point is that if this car is going to be the first indulgence into a cooperative effort for DC. What part of the car is the American part? If anything, the one part that has made American cars American over the past 50 years has been the V8.
We didn' t invent it but we did popularized it, so why not make the car with a V8.
Even the designers of the exterior are British, I mean come on!!!!!