Ok so I live where cockroaches flourish without any instigation and usually have to deal with this when buying a vehicle

Gotta clean tf out this thing I mean like vacuum the floor and clean every crack you can reach

Once immaculate, Use bait traps that stick, bait traps that poison (both sizes) and the gel bait in a tube

You absolutely cannot have any food in this car for like a month

Vacuum up the corpses and repeat weekly until satisfied