Thanks for your response Steve!
I would have preferred the is250 any time over the diesel, I love it. Unfortunately because of the high co2 emissions/KW and the reformed car taxes in Belgium this would have cost me 5 times what the diesel costs in road taxes and registration.
I hope with the new IS they do a better job in emissions and KW, like bmw (only 360 euro registration for a new 328i, used to be 2500!).
I drive a lot to Berlin which is 6h autobahn and it's crazy to be overtaken at 200kmh (top) by regular avensis, ford focus, etc.