I have a Penguino II (deLonghi from Sam's Club)
http://www.samsclub.com/sams/portable-ac-12-000-btu/prod5880055.ip?navAction=,
12,000 BTU in my 2-1/2 car garage. Here in KY, it is not only hot but really humid. I tried it venting out the window, but was not very happy about it or the location so I moved it and cut a hole to vent it through the wall. Last summer, when we were running heat indexes above 120, I was very glad that I had bought it. Although my garage is not insulated, I could really tell the difference when I had it running. I had actually considered installing in my 6x10 CT, but after reading other comments decided not to.
If I put my hand in front of the air being vented outside, I feel like I could cook with it, it is so hot. Inside, the air feels ice cold being blown into the garage. As a bonus, my unit can be set for a specific temperature, has a remote and a timer, that can be set to start up or shut down after a specific amount of time. This is the second summer for it, and I am still pretty happy with the unit.