I am not exactly sure though. It never hardens to a solid, it always stays soft. But it doesn't come over threw normal washes. I'm sure it hasn't changed to much. We have it in like a 25 gallon drum, and has a pump and a gun on it, works good but hard to get into tight spots. I clean my wheels wells everytime I wash my car and its fine. The U/C isn't to hard to get off when your using the right product. We have another product by AutoArmor. Its a adhesive remover. It says on the can, removes adhesive, undercoating, spots, and grease. It takes it right off. Works great say we get undercoating on the vehicles paint or anything else we dont want it on. We just get a rag and put some adhesive remover on it and wipe it off.
But replying to the OP. Save your money. Buy your own detailing supplies and do it your self if you have time. The dealership will charge you a arm and a leg since they have to make a profit.