I know you said no BMWs, but I was in a similar situation and when all things considered, tax, fuel etc I only have to pay £2 per month more to have a touring 320d se! The 318d is13% tax.
Another thought is go for a top spec A3 sportback with a tow bar or roof mounted bikes, the 2.0tdi is 13% tax! You'll save around £60 a month in tax!
I created a geeky spreadsheet, I'll email it if you want.
One other thing, the tax set up changes again next year…. Check out the AA website, it is quite handy to see what you'll pay now and next year.