Would like to know some benchmarks just to get an idea, like:

Petrol (diesel), MPG or KM's per Liter (average)

Versions horsepower (it would be awesome to get real figures to see the loss of power due to ageing but that's too much)

Most common problems (and avergage cost of repair)

It's just to get a picture, I understand things can be different, specially with old cars and countries.

I'm from Portugal and thank you all in advance