I live in Australia where we can get temperatures above 30 degrees centigrade for days on end during summer. This makes it quite hot inside my MGBGT. I investigated fitting air conditioning but wanted to keep my car as original as possible. Solution, a 12 volt evaporative cooler designed for campers and caravaners. I built a light weight wood shelf for the rear seat. Removing the 50mm outlets and fitting cooling hose to bring the cool air to the front seats works a treat. Then plug it into the 12v cigarette lighter socket. It’s not going to cool the car like AC but it provides air flow that is up to 10 degrees centigrade less than the ambient temperature!