Maybe instead of a battered old car you could get a concrete moulded version of a car made
This is a very good project you're doing, I'd like to ask how you approached your council with this, e.g. did you write a letter, or contact someone, write a business plan? I'm interested in a similar thing near where I live but never really was sure how to approach it, who o speak to. Any advice on this would be welcome.
Making trials type areas for all skill levels will be good if that can be added.
I think it would be useful if your site has some kind of cover, for the wet days,