My theory is all the glass is what causes the high temperatures in the car, and anything you can do to prevent that heat gain will help. The 2 products below others in the forum have mentioned. The sun shade I have had in many vehicles over the years, and it does lower the heat gain when parked. It is also easy to use, so it will be used more often.
To keep a car a little cooler when parked, you may want to consider a sun shade(I use this one
The Original Retractable Shade™) and I am not sure if these other shades would help for all the other glass (
Honda CR-Z ZF1 – Groovy Shades At least they are easily removable for times when you drive at night, which IMO is better than tint.