It's ironic, but true. If you leave blizzard plastic in a hot car this summer, you will not be happy with the results. Blizzard plastic is effected by the heat more than most plastics. I have already had one customer who lost a few discs to the heat. The flight plates warped from the heat.
Keep your plastic safe in the trunk and it's less likely to get hot enough to warp. A side benefit is that thieves have less reason to break into your car (no discs in the back seat to steal)