The XK5 hasn't quite enjoyed the same level of face-lifting and improvements as the other new Jag models which have totally turned the company around. The interior isn't as good as it is in other Jags either)
But it is sportier and will sound better (subjective of course).
Also you will be able to say you have a Jwaaaaaaaaaaaag (Top Gear reference).
Mercedes will be cheaper to run, service and insure (generally speaking). But it isn't as exclusive as the XK and to be honest the build quality of Mercedes is appalling nowadays (I've got 2 new Mercs in my household so have seen it first-hand). They don't quite have that well made solid feel to them any more.
But in the end it is a choice only the buyer should make, sit in both cars drive them about and choose the one which makes them happiest.
Last edited by Marc Fiorano; 02-07-2012 at 16:55.