Options for making my car much cooler

This document assumes that you've already checked your A/C functioning, and it is operating in top shape.

The thing is, I want my car to be much cooler than the car functioned from the factory. And no, it's not possible to upgrade your built-in A/C.

Changes that are cheap and not permanent:

• Slam the door three times.
• Use a sunshade on the windshield. †
• Use sunshades for all windows. †
• Use a large fan inside, and use a mist spray bottle. ⇒ Do this ASAP.

Changes that aren't permanent, but cost money:

• Install a ventilated seat cover. ⇒ Price this out.
• Use a car tent umbrella. †

Upgrades that are permanent and cost money.

• Install window tint, or infrared window glazing. ⇒ Try to DIY it at first — the worst that can happen is I remove it and pay someone to install it.
• Install remote start. † ⇒ Price this out.
• Spray-paint the roof white. ⇒ Talk to Tiffany, agree to some target level of quality.
• Install a swamp cooler on the roof.
• Something like the tent umbrella, but permanent, and that looks like an "inch of insulation with a solid surface". ⇒ Talk to Tiffany.
• Paint the outside with solar reflective paint.
• Add a radiant heat barrier into the door panels, floorboards and roof. [1]

Other random ideas: [1]

† Only helps when parked.