I have found that the few Mazdas I have driven and been in have higher levels of nvh than the competition. When I had the semis on the Mazda 2 it was crazy loud between 60 and 80. Luckily no need to travel at those speeds in a town car. Same tyres on another car were much quieter.
The stop / start is harsh on the Mazda compared to my car and the aircon doesn't work in the Mazdas when the engine is asleep.
However the Mazda 2 is a fantastic value for money proposition for a city runabout.
About the only issues I have seen with i30s have been loss of electric windows (pulley and wire mechanism fails, cheap and easy to replace) and another had intermittent central locking trouble and again a cheap replacement of the door switch fixed that. Look at the equivalent Kia too, same same and cheaper though I think the interioir can be lower rent. Son's mate bought a something GT (not stinger) and it was a pleasant thing.