if you can reach 2k then, either the 2.5 TD Omega in Manual form... as you will get much better mpg. You can also chip it, Omegatoy can get you one at a very reasonable price.
He got 30mpg with a fully laiden car and caravan!! i suspect a chipped manual TD can get 45mpg + fairly easily. An old user here called McBurger registered 47mpg on the fuel comp once with his 2.5 TD.
You other option is to go LPG, which uni are you at?? I am at Brunel and I living in Brackley, there is an LPG station here and there are several around my uni so if I had a V6 i would be tempted.
You could get yourself a nice 3.0 V6, and then get it LPG'd. The big V6's can do mid 30's on the motorway, little less running on gas, so 50mpg from a 3.0V6 is easily done
Since your doing motorway miles, the Omega is the best way to go. Thats why I got mine, so smooth and comfy blew my old Mondeo into the weeds in terms of comfort. It still has to be beaten, i have no driven another car yet where i feel as comfy as in the Omega