To be honest i cannot speak for the C3 but the Mazda 3 i can,My friends bought one a while ago now which had less mileage than my shoes and i was excited for them,i like Mazda's so was looking forward to them coming round to show me.
The car did look great and i was happy for them,although we went for a run and i sat in the back it was horrible,the seating felt really uncomfy the dash looked boring and horrible overall i was not impressed,but it may drive well so i had a go infact i drove it for a good while,no is was no better the performance was flat the seats again where uncomfy and just the general drive was a really bad experience,now i have to be careful here as i drive cars for a living so daily i drive a mix of cars and personally i own sporty cars,so performance may stand out to me comfort wise i can argue as said i drive sporty cars where the seats are often like rocks so for the Mazda to feel uncomfy was a shock.
As for the performance again i come from sporty cars,yet my friends partner had come from a 1.0l Fiesta,and the Mazda although a lot bigger engine than she was used to scared her with its flat spots,even more so as she uses main roads for work and she is to scared to overtake and when she has to slow down the Mazda takes that long to regain power other vehicles are tight behind her and scaring her.We looked at this on the net where people had said that they had tried to get that extra power dropping the gears all the time only to break there trans boxes.
Next prob was it had major fault on the brakes and exhaust again this car was like new but a phone call to the garage and these areas are not covered,me thinks they knew of these faults,so a like new car now cost them a ton off money to fix.
So overall i was not impressed,although i do see many owners say how good they are,but over 20 years on the road and a mass of vehicles i have driven i can only guess the Mazda seems good to them as maybe they have not driven many other cars and this is prob the best they have driven but a few decent cars to there experience more i bet would soon change there mind.