Personally I don’t think a 45 degree drop is unreasonable. The temp out the vent will be dependent upon the ambient temp. The system only removes heat, and its capacity to do so is finite, meaning that as the ambient temp rises so too does the vent outlet temp.
One thing it also does that makes it seem more efficient is that it removes moisture also. The dried cabin air doesn’t seem as hot, becuause it has better capacity to absorb moisture from your skin which is how your body dissipates heat.