The rules are that it can't be anything FOR the car; like a binnacle or some decent hats that don't have "delorean.com" taking up half the backside. No. This is a thread for impracticality.
I'll start it off by saying that I'm partial to the stainless steel DeLorean prison-style toilet.
They're already in use in many prestigious institutions like the Bossier Maximum Security Prison in Plain Dealing, Louisiana.