Now the B.S. begins

I could look but my wallet is empty.

Sounds to me like legally, at the very least your stepdaughter owes you 3k if you don't get your car back.
I'd be calling my local DA's office and file a complaint that you don't feel the case is being handled correctly as admitted by the current officer. (not following through on holding her responsible for selling a mutually owned asset.)
That was their own words, right?

Also as far as I see it, you having to pay fees to a guy that illegally bought the illegally sold car is not appropriate.
In a just world your stepdaughter and the buyer both should have to put the car back where it was and in the condition you say it was.
Otherwise restitution should be paid for any damage to your personal property.

Yea, I'd be making noise higher up for sure.

Oh screw it, I'll represent you for free.:D

Sorry about your predicament.
Sometimes family sucks.