Working on the interior of a '73 Barracuda. Wanting something different, looking to glue (expanded) vinyl to the door panels. Anyone have good success at doing this? If so what worked? The panels I'm using is a bit chalky at the top. Figured on some sanding then a spray adhesive to attach the vinyl to the panels. What brands work and which ones don't? Thanks in advance.

I would give the plastic a good wiping-down with alcohol and let it air-dry. A good spray adhesive should do the job (3M upholstery adhesive comes to mind….) just don't soak it on. Spray a light coating to both the panel AND the backside of the material. Allow it to set up for a minute, and CAREFULLY apply using a soft squeegee to get the air & wrinkles out.

Go slow and practice with scrap to get a feel for how the material will stretch and apply.

I have not found anything that will stick long term. The originals were made of polypropylene and are highly resistant to solvents and glues. From Wikipedia:

Many objects are made with polypropylene precisely because it is resilient and resistant to most solvents and glues. Also, there are very few glues available specifically for gluing PP. However, solid PP objects not subject to undue flexing can be satisfactorily joined with a two part epoxy glue or using hot-glue guns. Preparation is important and it is often helpful to roughen the surface with a file, emery paper or other abrasive material to provide better anchorage for the glue. Also it is recommended to clean with mineral spirits or similar alcohol prior to gluing to remove any oils or other contamination. Some experimentation may be required. There are also some industrial glues available for PP, but these can be difficult to find, especially in a retail store.

Good luck,
Craig

If you look at the back of a panel, it will say what the plastic is. Most automotive panels are either PVC or ABS injection molded. I don't think its polypropylene as that is more suited to blow molding (like washer bottles). For ABS or PVC contact cement will work.

There's always lag bolts!
Or 3M 80 or 90.
R.

Factory E-body door panels are made from Polyethylene (which is quite similar to Polypropylene concerning gluing something to it), you not going to find a glue that bonds to it permanently, its basically like trying to glue something to wax. Heat welding is the only true way to bond it.