I reckon it must be the seats themselves if you come out smelling like an old car. remove one, turn it upside down and have a whiff?

240K coupes had reasonable seats for the age of the car - sort of similar to the 240Z's seats. Maybe you could wash them while they are out of the car. I've done that with later model cloth seats, but with a vinyl seat it would be harder... you might have to look into getting them reupholstered and repadded? Or get some new seats.