Today I finally solved the mystery of the gas fumes in the cabin. The gas smell seemed to be heavy in the trunk, where the gas tank sits. Looking around I realized a few things:
- The gas cap washer was dried out and brittle
- The gas tank fill lines looked original to the car
- The defroster vent hoses were a mess
- One of the fresh air hoses in the engine compartment had a hole in it
Any or all of these things could have been the cause so I just fixed it all.