Not sure I should really talk about this, I'm maybe tempting fate.

Life expextancy of various parts of your car. I'm still running around on the same battery and exhaust system that was put in the car the day it came out of the factory in 2002 12 years ago. I don't know how long the exhaust will last before needing replacement but I was underneath the car last month and it still looked in great condition, a couple of bits of surface rust but nothing to be concerned about in the near future.

The battery I suspect is getting a bit tired in the colder mornings, I think this will be it's last Winter as the engine turnover is slower on cold mornings.

Apart from the usual oil/filter changes etc I have to say this Focus is one of the most reliable cars I've ever had in 47 years of driving.
I wonder how the newer cars are fairing now with batteries/exhaust, are they lasting longer or some models worse than others.

not bad at all, I had to change my battery done recently, swapped it after 7 years but it was on its way out! otherwise, most of the electrics side on mine is OK, just some connections dried out and needed rehydrating.

The battery is 12 years old and still cranks the engine? Good grief, that is amazing.

Our 2000 Focus 1.8 petrol LX still had the original exhaust system up until May this year when the rear muffler detatched whilst driving (not the most convenient time!) due to corroded mounts. As the entire system was so corroded it all needed replaced, but until it actually fell off it was in good order in terms of leaks etc...