Most rotors are cast iron - it's cheap and has good properties for brakes. Like you are seeing, the one property is does not have is corrosion resistance. Since there isn't much of a performance aftermarket for Metros/Swifts, I don't think you're going to find stainless rotors for it, and if you did, the cost of them would probably keep you from wanting them.
So, untimately I think there's not much you can do beyond parking it in a garage if possible.
Svoboy - where did you hear that Insights had aluminum rotors? Seems it would be a horrible material for brakes.
The Insight has aluminum (bimetal really) rear drums almost identical to those used on the '84-87 CRX HF. The body of the drum is aluminum, while the friction surface is the typical cast iron or steel or whatever it is they normally use. Instead of relying on thermal mass to deal with heat buildup, they have cooling fins around the perimeter.
I had a set of 1st gen HF drums on my CRX until I converted to rear disk and sold them a few months ago. Some pics I took for the buyer:
They're about half the weight of the stock cast drums.
I've pretty much stopped driving the car for the sake of driving the car. But I wasn't really expecting an easy (+ cheap) alternative. But you never know what you're going to get when you throw something at the GS brain trust...
Maybe I'll just use it as an excuse to start doing more tests again. At least that will be somewhat useful driving for the sake of driving. And it'll get all the other parts moving too. There are undoubtedly other potential problems I could avoid by not letting the car sit so much.
Not that the car isn't used to sitting - it sat unused for the first 7 years of its existence, although garaged.
Look for some rotors that don't have the high carbon steel. And Im surprised the metro's rotors foul/rust like they do. Or drums. There are lower carbon steel rotors out there. They wont offer the stoping power. But they do work.
09 HCHII, w/Navi
07 Mazda3 S Touring, 5MT
Mild Hypermiler or Mad Man?