Thanks Alkemi.
This is along the lines of what I was originally hoping to do. I had an open vat coated with teflon in mind, covered with a force field that would allow me to lower things into the superacid (fluoroantimonic acid), but keep the churning liquid and gases inside, to be be extracted once the solid was dissolved. The force field would be the same tech as on my starship hangar bays that allow fighters (solid objects) to move through, while keeping the atmosphere (a gas) inside.
Based on what I've learned here, the recycled materials will later be extracted by a means I don't plan to explain, since that's where the process becomes too complicated for my story. The temperature in the vat will be such that someone can walk right up to it. There will be an odor from the liquified vehicle (e.g., like the smell of rubber in a tire shop), but not strong enough to be toxic to humans.
For added simplicity, I may even do away with the force field, which rules out a superacid because of the explosive reaction and noxious fumes. I'll have to wave my magic wand and ignore the fact that bacteria or nanoids might release gases too. I'll probably have the liquid bubble a little for effect, perhaps from air trapped in the vehicle as it dissolves.
I ultimately plan to keep the process to a paragraph or two. Something a plant manager could explain to a visitor of a recycling center, without the process being totally impossible in nature. Let's face it, it's already improbable as hell. :-)
Thanks to all.
Dirk