I know it's probably not the normal time of year to ask this, but for those of you who may live or drive in the warmest parts of the USA, I was just wondering how's the cooling with 2 people in the 2014 Mazda3 (manual air conditioning)?

 

I can't advise you on a/c but i will advise you on transmission. If you get an automatic make sure you get an external auxiliary tranny cooler like the ones you get for towing. The cooling that comes with most cars is not enough -- the one that circulates through bottom of a hot 200 degree radiator doesn't cut it. This will be best for you in a very warm state in the USA.
Do not be fooled by "lifetime tranny fluids".
If it doesn't have one get one installed from a transmission place. This is not common on vehicles from the factory.

As a rule of thumb, every 20 degree increase in operating temperature above 175 degrees F. cuts the life of the fluid in half!

At 195 degrees F., for instance, fluid life is reduced to 50,000 miles. At 220 degrees, which is commonly encountered in many transmissions, the fluid is only good for about 25,000 miles. At 240 degrees F., the fluid won't go much over 10,000 miles. Add another 20 degrees, and life expectancy drops to 5,000 miles. Go to 295 or 300 degrees F., and 1,000 to 1,500 miles is about all you'll get before the transmission burns up.

If you think this is propaganda put forth by the suppliers of ATF to sell more fluid, think again. According to the Automatic Transmission Rebuilders Association, 90% of ALL transmission failures are caused by overheating. And most of these can be blamed on worn out fluid that should have been replaced.

On most vehicles, the automatic transmission fluid is cooled by a small heat exchanger inside the bottom or end tank of the radiator. Hot ATF from the transmission circulates through a short loop of pipe and is thus "cooled." Cooling is a relative term here, however, because the radiator itself may be running at anywhere from 180 to 220 degrees F.!

Tests have shown that the typical original equipment oil cooler is marginal at best. ATF that enters the radiator cooler at 300 degrees F. leaves at 240 to 270 degrees F., which is only a 10 to 20% drop in temperature, and is nowhere good enough for extended fluid life.

An auxiliary transmission fluid cooler is easy to install and can substantially lower fluid operating temperatures. The plate/fin type cooler is somewhat more efficient than the tube and fin design, but either can lower fluid temperatures anywhere from 80 to 140 degrees when installed in series with the stock unit. Typical cooling efficiencies run in the 35 to 50% range.

from: How often should the automatic transmission fluid... — Yahoo! Autos

Since your vehicle is new, flush and fill your automatic tranny every 25,000 miles.
From: http://www.motorweek.org/features/go...t_or_forget_it

 

Thanks for the tip.
I do admit, the previous model of 3 auto's have been quite reliable. I have a 2005 but the mileage is really low. Just over 40K. I had the tranny flush done at ~25K. It definitely ran much smoother after it was done.