I'd say between carpet and seats is where it's at, think about 30 years of sitting on vinyl seats in summer in stubbies shorts, becaus ethats all you could get in the 70's that and 30 years of farting, think about it. foam smell

and the back part of the rear seat has that organic fibre in it and if that got damp in the years that could start to rot and smell. get the interior re padded and re-trimmed and you should be okay. good excuse ofr some funky new seats from a late model car.