This past week, AutoWeek magazine did an article on the XTS.
Per the engine:
Overall the article stated the usual, "for that market" the XTS should fit the need. As if those wanting a roomy, luxurious and comfortable sedan were out of the mainstream of auto buyers, lol.The limitations of the 3.6L become more evident in hilly environments, where the need to rev all the way to 6800 rpm to acheive maximum horsepower makes passing a carefully considered affair.
It's not that 304 horsepower is inadequate. It's just that two tons of car is a lot for an engine this size to push around.