i have no idea how you could get 40mpg, best i've had was 28mpg average over a week of being aware of mpg.
window mech is another mentioned item i've had and the rebuild kits do work to save more money, but they really aren't ready to fit.

really are cracking cars, my misses is driving mine today, dead keen to get her hands on it again. it's only a 51 plate, so re facelift, but not much in them. i'm on 94k now and does feel tight.
i'd go for lower miles, i know it doesn't mean it's in better nick, but easier to sell on so could be worth spending a little more.