OK, it's not exactly a Mazda 3 but I own a Protege with 175K KM...
Overall reliability to 100K was excellent, then I got hit with tires, struts, shocks at the same time.... $1500 later...
Another supposedly common issue is vague "check engine" light problems. Over a few back to back visits they changed my catalytic converter, various engine seals and the O2 sensor. That worked for about 12 months then the light came on again...
Yet ANOTHER failed catalytic converter.
The first one had been replaced under an extended warranty, this time they wanted $1200... NO THANKS
The light is still on, and will be until I either trade the car or I need an emissions test.
Overall the car drives and handles very well. My only advice if you keep a car is buy the extended warranty. It will cost you an extra $1000 but it saved me a couple thousand bucks while they played around trying to diagnose the engine problems. I was told one of the bills would have been over $2000
