Stu.. it's not only for hot summer days..
It actually dries the incoming air, so demisting takes seconds on rainy days, in the winter, it's the same story, but you can have warm DRY air.. no more steaming up. and on a hot day... well, I'm not }) Especially as our cars have a lot of soundproofing, which is like an insulated jacket.. and mine being black doesn't help.. it used to be on gas mark 9 before I fitted the A/C.
All in all, it's the best £1200 I ever spent on my car.
stay cool, stay slinky })