I'm having some same issues as others. I have a Mazda3 with 95,000 miles on it and around both rear wheel wells the paint has started to bubble up. On passenger side the paint finally chipped away and had to use rust inhibiter and paint from Dr Color Chip to at least match the paint until I can get the spots repaired (about $350). There is a silver 4dr 2004 Mazda3 near my office that has 12" gaping holes around the upper edge of both wheel wells. I think this is a factory flaw, but then again this year was a first gen of this car so perhaps not the best foot forward on an new model. I do intend on buying a new Mazda 3 Speed in very near future. Oh and by the way gas mileage in the city (Chicago area) is amazing. Last fill-up almost 29mpg....awesome!!!.

 

yes it's a factory flaw!
2 pieces of metal join together and caulking fails.
It must be oil sprayed yearly from behind.
for more info read: https://www.mazdaforum.com/forum/maz...zda-6-a-31330/
i really took over that thread.

 

Up here in Ontario we got alot of people with the same problem. From 04-06 they got worse and worse and just driving along you notice that the rear quarters and the trunk are the first to go and then the fronts shortly after. When you drive with salt on roads it will inevitably happen. Although I have seen a few guys grind it out and re paint.

 

As far as I know, the problem with rust above the wheel wells continue on to the 2009s and maybe 2010s. I have a 2009 mazda 3 myself and I have to keep a close eye on them. Every year I get it checked over by a local mechanic just incase I miss anything myself and so far I haven't had 1 problem. It's just a design flaw, but easily managed if you keep a watch on it.