Mazda 3 has a solid AC
I live in Toronto, and belive it or not, its pretty darn hot in the summer over here. The Mazda 3 has an AC that is very good in my oppinion. There are vents even under the driver and passenger seats, so the back seats are getting cold air directly.
Its not a climate control system you'd find in a Mercedes or a Jag, where you can set 2 or 4 different climates in the car, but for the cost, and the size of the car, the AC is pretty good. I don't know how it performs on a 2.0L engine, but the one in my car is more then enough for me (I have a 2.3L). In extreme weather tinted windows may help as well (and they look slick too).
One thing that I hate about the car is that it does not have a built-in thermometer (inside or out)... I mean, if they were smart enough to put sensors for automatic wipers and lights, they could as well put a thermometer... i doubt it would increase the cost of the car by a lot...
Cheers!!