Sean, as a former chemist, I would recommed you contact a foam company. You could try Foamex. You want a company that makes it, not who fabricates it.
Try to bypass as many of the company's "suits" as possible. Ultimately, you want to get in contact with either an R & D, or a formulations chemist(very often, one and the same). They almost never get calls from the "real world", but are ecstatic when it happens. And, they are basically the only people in the company who have ANY knowledge of the product. How to make it, how to break it, how to make it last longer.
Just try to get past the receptionist, and have her route you in the right direction. If all else fails, just start dialing company extensions, and explain what you want. You are looking to talk to a foam chemist.
From my perspective, I would think the ultimate goal would be to find out what high boiling solvent is used in this type of formulation. You probably have polyether or polyurethane foam. The person on the other would know better than I. They would also let you know what should be applied.
Normally, you would want the same high boiling solvent as was used as the foam's plasticizer. A plasticizer is a high boiling solvent that keeps a polymer(the foam in this case), soft, pliable, flexible, sticky, etc. Otherwise, it would hard, brittle, and fall apart. The extremely high boiling point of the plasticizer ensures that the polymer keeps itself in good condition over the course of years.
However, it is a liquid. And, does evaporate, however slow. Eventually, it dissipates to the point where the polymer may crack(as in light fixtures), deteriorate, or just fall apart. Obviously, the extreme heat in a car interior makes this happen faster.
The general rule of thumb is that for every rise in temperature of 10 degrees Centigrade, reaction rate doubles. So, take it from there.
Plasticizers are usually phthalate(pronounced thal - ate) based compounds. For example, dibutyl phthalate, butyl benzyl phthalate, texanol benzyl phthalate, etc.
You also should add a bit of UV protection. UV does A LOT of damage.
Sorry to ramble on...
Anyway, be friendly to the guy. Don't BS him. Make him understand really quickly that you are not a salesman trying to have him try something. Ask for his honest advice. And, if you find good result, ask him to provide you with a 1 or 2 ounce jar of what he recommends. In my case, I would definitely provide it for someone in your situation. Just be sure to explain that you are a mature adult, and will not use the product in a means that will get yourself, or more importantly, him, in any kind of trouble.
If he is of help for the compound, but not in providing it, let me know. I can point you in another direction.