hey sharky!
you're totally right to be getting a diesel if you're going to be doing time on the continent. diesel is about 15-20 euro cents a litre cheaper over there so no matter how close a petrol car can get to the mpg, it's going to be smarter to buy a diesel.
the only problem with the bigger cars like the passats might be that the road tax is very silly, so have a quick look at that. gordon's right about the timing belt costs - that needs to be done properly and on time too.
don't bother with renaults, the driving position in any and all of them is considered torture by the european court of human rights
with diesels, you don't get a lot of car for your money. the petrol version will be cheaper (and with more toys), but if you're driving in europe the extra initial spend is worth it.