Unless you have a Crown Victoria Police Package, A/C's don't work worth a darn at idle RPM's, throw -er into N or P and rev it up to about 2K. So much for that fuel economy!
FWIW, had an Escalade that didn't do so good on vacation on an August Dallas Friday at 5:00pm. Not sure what the official high for that day was, but if the sidewalk had been 9% chrome, I would have struck an arc on it with confidence.....I'm so glad the ex convinced her lawyer to take it off my hands...I was gonna give it to her anyway, as a going away present, really I was.
Seriously though, if it is only 50F when cruising, you have problems. As Dave said they do set them up just above freezing, but a thermometer stuck into the vent should read around freezing to 40F max...
Since this is a weather thread
Got 8" - 10" of snow at Red Lodge Ski area (50 miles S/W of here) last night. One of these days I'll get to turn off the pilot light!