I've been there and indeed the mud is still in some places after a few years but i don't think it kills you're car.Sorry not interested. The reputation of the mud from Mammut park is very much known.
I have seen it first handed when we had meet up there.
It kills every cooler.
Take care of your car. It can be the last fun you have with it.
That's the Nice thing about it i think. There is a lot of (camping)space down the hill, and once u are up and over the hill there is a Nice playground.It's about the meeting, about the members, driving is optional and up to everyone on its own.
It's a park so you can go and look how the tracks are, ask others, take bypasses and what not.