The maximum penetration length of the liquid phase in diesel sprays is of paramount importance in reducing diesel engine emissions. Quasi-steady liquid length values have been successfully correlated in the literature, assuming that mixing of fuel and air is the limiting step in the evaporation process. Since fuel injection in engines takes place at high pressure, nonideal gas effects may significantly affect the phase equilibrium. In this work, real gas effects are implemented into the mixing-limited spray vaporization models of Siebers and of Versaevel et al., taking into account enhancement of the fuel-saturated vapor pressure by the high-pressure ambient gas. Results show that this effect is significant at ambient densities relevant for diesel combustion. The effect of gas pressure on mixture enthalpy (and thereby on liquid length) is also considered but found to be negligible for relevant diesel conditions. Since both models discussed are based on almost the same premises but give different results, their intrinsic differences are evaluated by deriving a new closed-form expression for the Versaevel model. It is shown that the models can be "equalized" by adding a correction factor to the Siebers model, making it physically more consistent. However, for the (limited) data set considered in this paper, this does not improve its predictive capability. It is argued that the remaining error in model predictions is most probably due to the cross-sectional averaging approach.