The Mondeo was on 150k miles and was 7 years old when I finished with it.
I have never said a major failiure is a guarantee. I've not (yet!) had a major failiure, just loads of minor ones at circa £300-£500ish each time. But the risk is there and your average £4k buyer cannot afford to swallow the bills - if they could why are they looking at £4k cars when a £6k one would be much better and so on and so forth?
You must be prepared for the possibility or it'll smack you in the face. If you are prepared and happy to accept that as the potential price of owning this sort of car, great, get one. I did and I have no regrets. I still wouldnt buy any other sort of car I love them so much.
What I'm trying to do though is make sure the sort of person who has £4k to spend on a car and finds a BMW for £4k and thinks 'Wow! I've got £4k!' doesnt find themselves getting burned further down the line.
The average cost per month of ownership of my car for everything but fuel and depreciation is running at about £200 a month. For me, this is a price well worth paying but it isnt as simple as just finding £200 a month because you need to have the spare cash in the first place to pay the odd big bill, which then averages out to circa 200ish as time goes on.
It's about making people aware. If people read me drumming into them what can happen and what it can cost, they look and think 'So what? If that happens, I can afford that, I want the car' then great. Buy it and you'll love it. I'd buy an E46 Coupe on a V plate over ANY Focus or Astra. People think German = reliability and this isn't the case. German = exceptional build quality, well engineered cars, great quality of materials but things still break - probably more than they need to. It's only because the cars are so good I put up with it. If it was just an A to B car I'd not buy another BMW. Even the new ones do it - just look at the tales of N53 and N54 engines with failing HPFP's, injector trouble, etc etc..
But if you look at it and think 'It probably wont go wrong, so I can afford it', then you should buy something else.
Does this apply to loads of other cars? Sure it does. And for those cars I know about, I post the same things there as well.
The thing that really brings it home for me is how actually buying a far newer, more expensive BMW with the benefit of the warranty works out as hardly any more expensive to own on a day to day basis as my older one does. I'm just using that to highlight a point, as obviously it isnt an option for people in the £4k market as you need the capital in the first place.