Personally speaking, I'd discount the V5.
To be honest, it has less torque than any of the quick diesels, and really isn't that quick. Doing a quick search on autotrader reveals that the cheapest in the country are starting at ?7k
That leaves you with one of the diesels or a 1.8t.
I would go for (un-biased here) one of the quick diesels:
The useless performance benchmark (0-60 mph) puts them on a par, but look at the in-gear figures - they are leagues apart. If you do a lot of motorway driving a TD really is the way forward.
And before anyone says the petrol car can be tuned, well so can the diesel!
I would get your ass down to a main dealer, who has a stock of all of these cars (even if you don't plan on buying from here) and drive them all, back-to-back, over a mixture of roads, making sure that you take in some motoorways, as this is where you spend your time.
On a personal note, driving a diesel I
do actually miss ringing the nuts off a car. But then, when I'm sat on the motorway, I fl;ex my foot and my car pulls like a train in 6th at 100mph I'm glad I went for the diesel
