you could also use trees, are woods are full of old fallen trees, just trim the branches and make poles and stack-em large to small and dirt on top, they rot after a few years but you can add dirt as they do, and no oil or rust to contaminate the soil. as far as noise, as long as there is no ordinances(check with township) against it, you should be alright.

 

Here in Iowa there is a new law that prevents anyone holding the land owner responsible in and sort of acident when they let someone use there land for any sporting activitys (it mentions ATV's), as long as he is not charging a fee. It has made it alot easier to find places to ride if the farmer know that they are protected against any lawsutes. It is "Code of Iowa 461C. You may check to see if there is something like that in your state. Here is a link to it
CHAPTER 461C PUBLIC USE OF PRIVATE LANDS AND WATERS

As far as the noise, you may want to go make freinds with them before you start.

And for the cars I called a junk yard and as them, They said that they would have to charge for the ones off the lot but he had a whole list of cars that he needed to pick up from people and if I wanted to get them insted I could have the for free. I just borrowed a trailer and a wench and had a few of my riding buddys help me go and get them.
Its well worth the time.

 

I've used buried cars for years. My friends thought I was nuts. I'll let them pay for fill dirt. I've got a really good 350 buick motor for sale, all you need is a shovel.

 

Run over the table tops a few times with the dozer when your done.

 

Did you bury any EX friends in the cars??? LOL