04 or 05 Passat should see you right.
We've got a 4Motion TDI 130 and it's a truly great car.
Avoid the new shape Passats - they're just bloated Golfs and have stupid stuff like an electronic parking brake (which apparently goes faulty a lot). The B5.5 has a longitudinal engine and is based on the Audi A6, so is built like a bank vault.
The 4Motion also handles pretty well for a big ole barge. This was us a couple of weekends ago:

130 PD motor will chip up to 150-170bhp easily. I've not got ours done yet though - 130bhp and 40MPG is good enough for a daily for me.