Well, if I've read this thread right, the OP covers 10,000 miles a year odd, but wants a car that's reliable and, most of all, has a budget of up to £4,000.
At that price, you're far more likely to find a well looked after petrol powered car.
Then again, like nearly everyone else in this thread, daugirdas really wants an underground airship - the impossible!!
I don't know how uneconomical his 1.2 Clio was, but I'm commuting around London in my 17 year old daughter's 1.2 Clio until she passes her driving test and it's giving me 42-44mpg which strikes me as acceptible for any car.
I'd say (and voted) for the Octavia 1.9 105 as I think it best suits your requirements. I wouldn't bother tuning it either. Plenty of power for hills with common sense e.g. trying 5th gear at 20mph on a 1in5 is not the cars fault it wont turn out well. You might not win as many traffic light GPs compared to the 140 but do you really need to compared to the better fuel consumption. I see from the voting I'm in the minority though- always a good sign- wouldn't want to be accused of selling out
Get out of here with your common sense and reasoning
I think we need some perspective in this thread. Let me sum things up in 11 easy-to-understand points:
1)
From your list, the Superb is the best car. Fact.
2) Diesels were designed as economical engines, nothing more. The OP wants something reliable and economical.
3) The 1.9TDI engine is the best pick in this regard.
4) Tuning them, for his requirements, is absolutely folly.
5) They ARE noisier and less refined than the equivalent petrol engines.
6) Yes, you can always tell you are driving a diesel, unless you are deaf and/or blind. An appropriate analogy would be to state that you can't tell the difference between ISO100 and ISO3200.
7) No, you won't get 105MPG unless you drive a 3 cylinder Smart ForTwo CDI and never exceed 55mph.
8) If you can't drive a petrol-engined car in a hilly environment, you need driving lessons.
9) For £4,000, an Alfa Romeo 156 is absolutely not the best choice to make. And before you say it, yes, your car may have been reliable, but are you familiar with the concept of statistics?
10) If you listen to, and subsequently follow someone's misguided advice that 90bhp in a small car like an A-Class is somehow "inadequate" or unsafe, then the car isn't the issue.
11) The OP has UP TO £4,000 spend. This is cheap car money. He clearly wants something hassle-free.
OP, you sound like someone who couldn't care less about running cars and wants absolutely the least amount of fuss. Hassle-free motoring. Cars with complex mechanics (i.e. modern turbocharged engines and high pressure this, that and t'other) are great when you can hand them back to the dealer or lease company, say "fix this under warranty please" and drive off in a hire car. Otherwise, you need to a) be doing lots of miles in order to offset the increased running costs or b) be an enthusiast who appreciates that running cars as a hobby is expensive.
Buy a petrol Focus. It's the best choice for this scenario. Fact.