I haven't had any trouble with the original beta-test version on Turtle (n.k.a. Dr. Horrible) or with the one I now have on Ron Burgundy, and there's no way it's any hotter in Cali than it is in central Florida.
Then again, I use an SUV sun shade to cover the rear windshield over the IMA compartment, a regular size sun shade on the front windshield, I throw a towel over the leather seats (since I have a sun roof), and I crack the windows about 2 inches (courtesy of the rain guards). It's actually not too hot when I get in the car in the afternoons.