Welcome, kulot!
Sounds like you are looking after your car well.
Steering vibrates when braking at 80kph+ (I assumed rotor worn out, but very unlikely to worn out at 31k kms)
Rotors are probably not worn out, but if you have a little corrosion build-up, it will do that. Mechanics here used to turn rotors on a lathe to clean up the surface if warped or corroded, but since Chinese car parts are so cheap, nobody does that any more.
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View my fuel log 2014 Mirage ES 1.2 manual: 62.4 mpg (US) ... 26.5 km/L ... 3.8 L/100 km ... 74.9 mpg (Imp)