Welcome! I originally thought the same way your mechanic does. Figured the cheap Mirage would start having issues around 200000kms if not sooner. That doesn't seem to be the case.
Do you know what was the highest mileage ever recorded on Mirage?
Vovanchik and Mirage Musya
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View my fuel log 2017 Mirage ES Plus 1.2 automatic: 40.3 mpg (US) ... 17.1 km/L ... 5.8 L/100 km ... 48.4 mpg (Imp)