Defect or "External Influence" with Melted Plastic

That is seriously weird. Never seen or heard of that problem before on any car, foreign or domestic.

 

I can understand how the service manager formed that conclusion. It looks like it was parked next to a fire or, perhaps, a radiant heater. I once had a plastic bumper cover damaged by a car having a ruptured radiator that sprayed out hot coolant. Is all of the damage on the same side of her car?

 

Does the car get parked where the sun reflects off of high efficiency thermal pane windows onto the car? I know people in my area that have had partial melting of garbage cans from the reflections.

That's a long shot, when that happens the damage is usually in a longer horizontal line from the reflected image moving as the sun moves.

 

Not likely.

 

A long-ago coworker with a different brand car received a hole in her plastic bumper from the exhaust of an idling SUV or pickup parked much too close. But it did not look similar to this.

 

That's what I thought. Didn't the LA concert hall have to be modified due to similar issues: USATODAY.com - New L.A. concert hall raises temperatures of neighbors

 

Reflection from a window is my guess too. You can do a search on how newer high efficiency windows are melting vinyl siding in adjacent homes. Here's an example:

Window Reflections Can Melt Vinyl Siding | GreenBuildingAdvisor.com

 

Like others have said. I think it may be due to high efficiency windows reflecting on the car. I've heard of other reports of this issue on the news.

Woman Claims Neighbor’s Energy Efficient Windows Are Melting Her Toyota Prius « CBS Los Angeles

 

OP doesn't say where in Calif. car is driven? Having a dark car in the desert might be a contributing factor, but obviously is not the complete story.

Regarding reflection from low-emissivity glazing, my partially open casement window reflected enough radiation to distort my vinyl siding -- and I'm in NJ.

 

I certainly wouldn't rule out vandalism. The damage is so localized that it is very suspicious indeed. A natural occurring anomaly or a heat proximity event would have most likely caused some sort of paint blistering in the surrounding areas.

 

Excerpt from Wikipedia Prius Gen III:

"In constructing the Prius, Toyota used a new range of plant-derived ecological bioplastics, made out of cellulose derived from wood or grass instead of petroleum. The two principal crops used are kenaf and ramie. Kenaf is a member of the hibiscus family, a relative to cotton and okra; ramie, commonly known as China grass, is a member of the nettle family and one of the strongest natural fibres, with a density and absorbency comparable to flax. Toyota says this is a particularly timely breakthrough for plant-based eco-plastics because 2009 is the United Nations’ International Year of Natural Fibres, which spotlights kenaf and ramie among others."

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Do you know for a fact that bioplastic melts easier?

 

It appears the two spots had a concentrated heat source very close to their locations, whether intentional or not. I agree with Toyota not covering under warranty. Was it parked next to a bonfire or heatlamp? LOL Figuring out what the source of the heat was may lead to who is ultimately responsible.

 

No

 

Looks like it was Death Valley.