An A/C unit puts out a 100% cooling effect when it is running, so the system adds warm outside air in most autos to moderate the temperature or cycles the A/C full on or full off (as in the case of a house) to get a moderate cooling temperature. It seems inefficient to have the A/C running at 100% when it is not needed. The peltier chips would not have to be run in such an inefficient manner. You might only need to use half the number of installed chips when cooling at a moderate temperature. If you want more cooling, you bring more chips online.
It's not inefficient to run something at the point of maximum efficiency, or not at all. In fact, that's the most efficient way to do it.
Now that could be legit. But there are variable-speed central air units now. Maybe variable-speed car A/C units are possible.