Vectra CDTi 150..... They're worth about as much as a 306 HDi, just as unreliable, only do around 50mpg like the HDi, but do have more spec.........and are fecking massive lol, 2.4metre lentghs of wood fit in there no issue.....in the HDi hatch they were wedged between the windscreen and bootlid. 
But seriously, neither of the above. As has already been said, decent HDi's are very few and far now, most won't be that economical either as they have sensor issues, boost leaks and faulty EGRs, I've owned 3 now that wouldn't get above 50mpg....shite considering the lack of power, even at stage 1.
Golfs are overpriced as you say, shame because there's so many about that its easier to find a looked after one (for most people haha). The Mondeo is a good shout though, although they do have a DPF I believe (unlike the MK4 Golf, Vectra or 306 HDi) but with £4k to play with I'd want something better than a boring family car tbh....
But seriously, neither of the above. As has already been said, decent HDi's are very few and far now, most won't be that economical either as they have sensor issues, boost leaks and faulty EGRs, I've owned 3 now that wouldn't get above 50mpg....shite considering the lack of power, even at stage 1.
Golfs are overpriced as you say, shame because there's so many about that its easier to find a looked after one (for most people haha). The Mondeo is a good shout though, although they do have a DPF I believe (unlike the MK4 Golf, Vectra or 306 HDi) but with £4k to play with I'd want something better than a boring family car tbh....