It seems counter-intuitive, but I can attest that simply placing items on the car floor under a couple blankets will keep items cool for quite a few hours, assuming the car interior is cool to begin with.
As long as it is not above the catalytic converter nor the muffler.
Warning!! Handling a Hasselblad can be harmful to your financial well being!
Nothing beats a great piece of glass!
I leave the digital work for the urologists and proctologists.