Running costs

Heya folks,
Quick question. We're getting another addition to the family at the end of the summer so money is going to get tighter. I bought a 2005 A6 2.0 TDI about 8 or 9 months ago and I've found the maintenance costs to be fairly high (I put 100 quid by a month just for maintenance and I'm playing catch up) and I wondered would it be cheaper to run a 2005 or so 1.9 TDI estate passat. After having an A6 I'd want to keep the massive boot. My other half has a mini and she can't even fit the pram in.

It will be more economic, but it will be slower, on the up it's a better engine.

I had noticed that alright. About 30bhp in the difference. In what way is it better?

The passat is an expensive car to run if things go wrong. The lower the spec, the less to go wrong. The 1.9 engine has less common faults than the 2.0 pd tdi. With any b6 passat you still have expensive to fix; electric park brake, clutch/dmf, steering column switch faults all of which are common and are in the £1000 price fo a fix. Like any large car, tyres are not cheap.
In some respects a b5 estate might be cheaper to run.