Thanks to all for your comments.
I honestly didn't want to rake up the rust issue too much, the question was framed really as to whether there was any change in the administration of 'claims' from my previous experience. John's points are of course valid - but if my Vauxhall goes rusty within 6 years of manufacture (I've got 2 left) it'll be in to see the dealer, because the paperwork says it's under warranty. I guess I'm as fair as anyone else - I wouldn't try to make a claim for rust caused by damage. I certainly
would buy a second hand car and take it back to the manufacturer under warranty to remedy manufacturing defects though; the Mobilo arrangement is attractive to the second hand buyer and IMHO bolsters the used prices significantly.
Sounds pretty undivided then - power (or rather torque) corrupts. 320 wins hands down?
My previous W210 220CDI was extremely economical, but I've got to say that it did the 'Mercedes smooth' thing well but without a real feeling of grunt behind it. I want something that does smooth with a bit of grunt on demand - I'm normally a feather foot anyway.
As to use, it would simply be a family car, with more space than I have at the moment, and the capability to tow a car trailer when I need to (not often enough to warrant a manual box). I get about a little with work and have the option of a hire car, or to use my own and claim 40p a mile, whichever is cheaper. My Astra essentially pays for its entire fuel budget through work mileage.
So to the other side of the question, are there any differences in reliability between the two engines / transmissions? Any ways to spot a bad one?
Also, am I likely to get a decent W210 320CDI for my approximate budget of £7k? I am picky, so I don't want a well worn private hire car.
Cheers,
Ian.