Not to start a debate, but there is a huge difference in manufacturing practices, and most notably the details that companies use. You can oil spray and help prevent rust, but poor designs will prevail.

An example of this can be seen in some newer vehicles, where companies have started to use a soft, carpet like material in the wheel wells of vehicles to eliminate road noise. This material will absorb moisture and hold on to it, slowly allowing the metal well to deteriorate. Oil Spray may help prevent moisture getting to the material, but if any does get through, it's now doing more harm then good, by not allowing the moisture to leave.

As a side note, I believe the mazda3 uses the carpet like material in their wheel well, but I can definitely be wrong.

Yes Galvatron is right. Although earlier Mazda 3s had actually had rusting problems which a recall later fixed.

the only thing i know i have a 2006 sebring and a 1994 acclaim (my father in law use to own it) and non of my car have rust on it, because i oil them, he owned a shit lot of cars in is life and non of them ever rusted (he still have 3 chrysler Reliant with no rust on the land at the farm). i understand bad desing and everything, but im sure with proper oil process( installed before first winter) so you dont put oil over the salt. anyway grease you car and you will minimise the problem if not get rid of it. i never had a rust bucket and not planning to have one. sorry i was rude because i never say congrats for the new car. i never been a mazda guy ( i know i own a FD) but rotary is different of pistons, i'm more a dodge guys as for piston engine, but thats an other debate. i hope the skyactive is good shit, i wouldn't mind trying that, if it actully live up to what they say about it.

congratulation and you did the smart move with the apprenticeship, i have 2weeks left of school before i become journeyman and i just got a good friend of mine who is a member of the forum also into my trade, best thing i did in my life. because of that i can afford my Financial Disaster

Mazda 3s have plastic inner fender liners in the front, none in the rear.

Mazda 6s have a fuzzy carpet like inner fender liners in the rear.