i'd lean more towards the car scrapyard (assuming you're meaning actually putting a bunch of wrecked cars around the place) plywood is handy enough but not quite as atmospheric, plus it likely won't last as long.
Would insurer's not kick up a fuss over the scrap car yard? Given the increase in accidental injury, etc. It'd be much cooler than plywood maze, but it's whether you're able to do it I guess.
Both would have to be adapted to be safe, but got a lot of people wanting different things so wanted to see what the wider community thought
plywood is handy enough but not quite as atmospheric, plus it likely won't last as long.