Way out of budget unless you will accept finance but....
BMW are doing deals on BMW520ED new builds.
Tax Band C = £30 a year.

Warranty = 3 year or 999999 miles

MPG = Claimed and realised ~800miles per tank

Have a look on autocar and there is a section there where a broker has agreed for lots of extras to be included at no extra charges.
If I had to choose a next car, this would be sitting at the top of my list by a long long stretch.