I have just sold an 2003 130bhp Passat TDI. Paid £3,500 for it 2 years ago with 58k on the clock. Has been pretty reliable, but be warned servicing costs have mounted up.
I never changed cam belt (we sold it with 93k on the clock, so it was due). Regardless of this I spent circa £1.5k in servicing costs over the two years and there were some additional work that I would need to have had done if it was still mine in 6 months, which I recon was another £600 + as a minimum.
Still, probably cheapest motoring I will ever have. Have a company car now, so paying £££ tax for a thirsty Nissan Juke turbo petrol. Passats are quite common on ebay and according to the garage people keep TDIs going for 150k + no problem (they were servicing an Audi A4 TDI with 250k on the clock, still fine).
Also had a Mondeo TDI hatch (about 7 years ago, great car, put a large bike in the back with no need for wheel removal). Would happily have another.
If I were buying a newer car, I would be tempted by a number from the Skoda range, including Roomster, Octavia estate or Fabia estate. I have had roof racks on my Passat (and now Juke), so this has knackered fuel economy, but big estates swallow a bike no problem and some of the skodas can be had with clever upright bike mount things, so you can keep the bike upright in the back, fork bolted to a qr skewer.