The linked document shows humid air having an enthalpy of 75kJ/kg at 25C, so that explains why humidity increases perceived heat and increases the energy needed

The linked document shows humid air having an enthalpy of 75kJ/kg at 25C, so that explains why humidity increases perceived heat and increases the energy needed to heat up humid air, but the heat itself is coming from car engines, and the humidity from tailpipes. On the whole, i don't find underground carparks notably humid, but they are warm.