Plastic melting on Tacoma for no reason...

That looks caused by heat, not chemicals.

 

I would look at my neighbors houses and surrounding area. Look for Low-E Windows.

Oh, and modern AC and heat Pumps do not use Freon. Freon has been outlawed for years.

 

Just to back up the Low E claims, I have a pool storage box (a Lifetime brand) parked on my deck next to my window, and where the sun reflects off the window it's melting the cover. You can actually feel it from 50-60 feet away from the window. It's pretty intense.

 

That's exactly what it is. I have repaired vinyl siding on dozens of houses where high efficiency windows were the culprit. It doesn't have to your house, I've seen it happen from houses across the street. Never saw vehicle damage, but I have no doubt that is the cause.

 

Reminds me of this picture I saw.

Person who posted it said a mirror was left in the car and as the the day went on so did the focal point burning a line in the headliner.

 

I inspect homes for a living and see the melted siding all of the time, whether due to gas grills too close or reflected sunlight, so yes, i can attest to that being a common occurence.

 

Aliens!!