I do own both engines XF 2009 4.2 and 2011 5.0 and the difference is huge, MPG increase a little my commute is 34 miles a day 80% freeway the 4.2 gives 26 MPG and the 5.0 24 MPG

 

Isn't the 5.0L rated higher for MPG than the 4.2L? I know the 5.0L SC was rated higher than the 4.2L SC. I have noticed that the 2012 XF 5.0L (NA) loaner I was driving around gets about the same gas mileage as my 2009 4.2L Supercharged which doesn't line up with the ratings I've seen.

After driving the 2012 XF 5.0L for a while I do really like the 2012 changes. All the small annoying issues the dealer can't find or fix on my 2009 are not present on the 2012. I love the front end and headlights. The nav/entertainment system has really grown on me. The USB sticks that don't work in my 09 work fine in the 2012 plus it plays all my Top Gear videos on the screen.

If someone was looking at a 2009 XF (NA or SC) vs. a 2012 XF 5.0L (NA) I'd say go with the 2012. Even though I really love my 2009 SC I'm sorry to say that the 2012 (overall) edges it out. Of course price couldn't be a factor because ~$25k more for a 2012 is a good chunk of change.

 

Rumor is that all the defects uncovered in the first series of XF cars have been corrected in the facelift model. So much so that it is more like a new version than a facelift.

 

I totally agree, the XF 4.2L SC is far more enjoyable than the XF 5.0. I own the natural aspirated 09' 4.2 and fine it more than adequate for everyday driving.

Yes, the XF 5.0 is significantly stouter than my 4.2; however, I will take a 09' 4.2L SC over the 5.0 just for the "fun factor"....pray for no more traffic tickets.

 

There was an AMG S63 next to me the other day. I couldn't let him get ahead of me. He didn't know we were racing, but I smoked him anyway.