I believe that if you search the archives, you might find something that will give you an idea.
IMHO, I wouldn't. If Paulsons can be unwarped with the application of heat, I think you can just as easily warp them, or any other clay chip for that matter. the application of heat is one of the essentials of making the chip in the first place. I also think that the little care instruction sheet that comes with the ASMs specifically mentions
not to leave them in a car.
I just think you'd wind up with a warped, awful mess.
Maybe some Faux Clays, Sopranos or even NexGens would be a better option.
Ooohhh... there is the whole chip bake off experiment and thread that Ten did many moons ago.
http://www.chiptalk.net/x-poker-chips-Bake-Off.html
Even in a non-desert environment, the interior of a car can get well over 100 degrees F in short order. I know in the worst of the summer in Arizona, the interior of my car (which has great tinting that blocks 99% of the infrared as well as a sunshade I deploy across the inside of the windshield/windscreen) gets abusively hot. Each year, there are stories in the news here of pets, and even worse, children who are left in cars for even ten minutes and wind up dying from the heat.
Not that a chip has the value of a child, but I'd never leave my ASMs in my non-running (with air conditioning) car any longer than I absolutely have to. I'll specifically plan a trip to drop off the chips at their destination before running any other errands before poker night (like, buying beer).
Just my 10-cents. In short, leave them in your car at your own risk.