Your target is all over the place. The Hyundai is not light, the Toyoburu is not luxe enough to play in that company.
Take the S550, add $10K to the base price and put it on the F-150's weight loss program (-500# as a target?). Stick a more compliant but still competent suspension tune under it, throw a few more cows into the interior, de-muscle and class up the front and rear fascias, and you've got a Lincoln that can compete with the Audi, BMW, Jag club. Especially if we ever see a stretched four-door variant on the platform...